Identifying and Reducing Workforce Fatigue in Rapid Renewal Projects (2014)

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92 A p p e n d i x C This appendix identifies and discusses promising techniques for fatigue management and mitigation in highway renewal projects. This material was reviewed in terms of the evidence supporting the impact on worker fatigue and performance and in terms of the potential applicability in the highway con- struction environments the team observed during field work. Factors considered included demonstrated impact on sleep and performance, the extent to which laboratory studies can be generalized or implemented in field settings, the existence of field studies, enhancement of worker knowledge, and the over- all preponderance of evidence and clinical experience. There have been relatively few “pure” field studies of fatigue counter- measures in the traditional experimental design model. Instead, much material is based on laboratory studies of controlled sleep duration, simulated performance tests, and field studies of fatigue reports or error in shiftwork populations. Thus, countermeasure recommendations are usually a result of syn- thesis of clinical experience, observation of trends, abstract experimental studies, and model-based sleep/wake regulation and circadian rhythm principles. The result is a list of fatigue countermeasures that are categorized according to a general “effectiveness” metric, which combines the team’s assessment of the strength of evidence concerning impact on fatigue and performance, the duration of that impact, and the likelihood of application and adoption in the highway construction envi- ronment. This last aspect is essentially a judgment based on applied research and engineering knowledge and is meant to reflect the practical aspects of countermeasure application. An additional classification for a number of counter- measures is “limited evidence or implementation complexi- ties.” This category was used for countermeasures that should work in principle but involve considerable technical com- plexity for implementation, have not been shown to impact fatigue or performance empirically, or entail medical super- vision such as hypnotics and stimulants. We adopted a classification scheme originally proposed by Co et al. (1994) for fatigue countermeasures in aviation operations. They distinguished preventive and operational countermeasures. Preventive countermeasures are used to “maximize general alertness” and tend to be used in off-work settings. Operational countermeasures are employed in the actual work setting to mitigate the effects of acute fatigue. While there are clear beneficial effects of many of the counter- measures to be discussed, Co et al. (1994) point out that there is no “magic bullet” for fatigue prevention and mitigation—it is important to take an eclectic approach, and to use measures that have been shown to work and that are adaptable to the circumstances at hand. Table C.1. lists the countermeasures identified within the classification scheme described above. The subsequent pages of this section discuss each of these countermeasures from the standpoint of overall impact and potential implementa- tion in the highway construction environment. This discus- sion is not meant to be a comprehensive review of evidence and individual research study parameters, but key references to selected studies are provided. Substantial portions of this section are based on material from McCallum et al. (2003), Dawson and McCulloch (2005), and Caldwell, Caldwell, and Schmidt (2008). This section is written in predominantly non- technical language to facilitate the development of material appropriate for the operational environment. 1. Adequate Sleep Preventing fatigue by ensuring adequate sleep opportunities, proper sleep-period timing, and appropriate accommodations. Type of Countermeasure: Preventive 1.1 Basis The most effective countermeasure for fatigue is to do as much as possible to prevent it from occurring in the first place. As the material in the literature review suggests, the Fatigue Countermeasures

93 primary culprit for feeling fatigued is sleep loss. So, whatever can be done to obtain regular sleep and to prevent sleep loss should be high on the list of countermeasures. The principal advantage of getting enough sleep is that it will reduce on-the-job fatigue, thereby reducing the need for other countermeasures. People tend to need, on average, 7.5 to 8 h of sleep in order to preclude feeling fatigued. While there are individual differ- ences (Tucker et al. 2007), and some or complete sleep loss does not automatically lead to unsafe performance, it has been amply demonstrated that acute or chronic sleep loss leads to fatigue and safety risk (Van Dongen and Hursh 2010). Further, continued sleep loss results in cumulative effects (Van Dongen et al. 2003), and takes more than a single full sleep episode to recover from (Belenky et al. 2003). Hours-of-service rules tend to be based on the idea that restricting work time will provide sufficient opportunity for restorative sleep, but this idea does not hold up well to practical experience (Gander et al. 2011). The first general strategy for minimizing sleep loss is to establish a routine approach to obtaining sleep that allows enough time to obtain sufficient sleep, takes time of day (cir- cadian rhythm) into account, and ensures an appropriate sleep environment. Ideally, this would mean going to bed at the same time every night and waking up at the same time every day, allowing for at least 8 h of time in bed. This regularity, if properly linked to the individual’s circadian rhythm (e.g., morning- and evening-types; Kerkhof and Van Dongen 1996) makes it easier to go to sleep, wake up, and recuperate fully each day. Recognizing that regular sleep times are often not congruent with everyday life, it is important to point out that day-to-day variations in sleep timing and duration can be overcome by sleeping in on days off (Banks et al. 2010) and by supplement- ing sleep time with napping (Mollicone et al. 2008), provided that total sleep time is not curtailed in the long run. This is not recommended in individuals diagnosed with insomnia, where sleep regularity is one of the pillars of sleep hygiene and typi- cally considered essential for treatment. The sleep environment should be quiet, dark, and of com- fortable temperature. Shift workers often change shift sched- ules from one week to the next or more frequently. This can lead to sleep loss because the brain is not adapted to sleeping at a different time of day. The best approach for reducing sleep loss associated with a new shift schedule is to start the new shift with no sleep debt. As a rule of thumb, this means getting at least 2 nights of unrestricted sleep before beginning a new schedule. If making a radical schedule shift, such as between days and nights, it will also be important to obtain some com- pensatory sleep prior to the new shift start (see discussion of defensive napping). For example, if the schedule starts at mid- night Sunday, it would be desirable to get two full nights of sleep on Friday and Saturday, sleep as long as possible on Sun- day morning, and try to nap for a couple hours before the start of the midnight shift on Sunday. Napping before extended periods of wakefulness will reduce fatigue and improve alertness. A third general approach to minimizing sleep loss is to match sleep and work schedules to individual physiology. Morning people (i.e., “larks”) perform best on work sched- ules with morning starts, but even for young people earlier than 7:00 a.m. is difficult. As an example, a study of construc- tion workers on a typical three-shift system found that the day-shift workers got the least sleep, due to the 6:00 a.m. start time (Powell and Copping, 2010). Night people (i.e., “owls”), perform best on work schedules that start in the afternoon or evening. In either case, it is important that individual physio- logy be coupled with a sufficient main sleep period. Countermeasures to Minimize Sleep Loss: • Obtain sufficient sleep • Have a regular routine for sleep • Ensure the sleep environment is appropriate • Start new shift schedules with minimal sleep debt • Obtain compensatory sleep before new schedule • Match regular work schedule to personal physiology: “lark” or “owl” Table C.1. Fatigue Countermeasures Classified by Type and Judged Level of Effectiveness and Implementation Complexity Impact Countermeasure Type Preventive Operational Generally Effective • Adequate Sleep • Defensive Napping • Good Sleep Environment • Limiting Overtime and/or Work Sched- ule Modification • Caffeine • Napping • Anchor Sleep • Rest Breaks • Fatigue Education Less Effective • Diet • Temperature and • Ventilation • Self- and Peer- Monitoring • Exercise Limited Evidence or Implementa- tion Complexities • Hypnotics or Stimulants • Model-Based Schedule Optimization • Fatigue Risk Man- agement System • Worker Status Monitoring and Alerting Technologies • Bright Light or Melatonin for Cir- cadian Shifting

94 The limitations associated with this countermeasure tend to involve factors that often are beyond the control of the individual, such as work-shift start times, rotation of sched- ule, and location factors that might influence sleep, such as jet lag or the sleep environment. Additionally, some individuals tend to sacrifice adequate sleep for purposes of social or fam- ily activity; however, these factors involve individual choice and can be balanced as required. 1.2 Effectiveness It is generally agreed in the fatigue research literature that adequate sleep is the most effective countermeasure to fatigue and performance decrements. The effects of adequate sleep last throughout the work period unless the work period is so long that it requires wake extension and thus causes sleep deprivation (although circadian rhythms will increase fatigue at night regardless). 1.3 Highway Construction Environment Implementation Implementing the preventive countermeasure of adequate sleep involves a combination of worker knowledge and work sched- ule management to provide sufficient opportunity for sleep. As such, linkage to other countermeasures such as worker educa- tion and schedule management on the part of the construction contractor are important elements in getting adequate sleep. 2. defensive napping Defensive napping as a fatigue countermeasure involves sleep- ing for a brief period prior to the work shift. Type of Countermeasure: Preventive 2.1 Basis Taking a nap can help to reduce fatigue and increase alertness on the job or at other times. Naps can be effective as a short- term countermeasure to fatigue or to compensate for periods when a worker will need to remain awake for a long time, such as when changing shifts. Some general situations where napping would be appro- priate are • Less than 6 h for the main sleep period; • Awake for 30 min or longer twice or more; • Feeling as if continually drifting in and out of sleep; and • Feeling much more tired than usual upon awakening from the regular sleep period. Taking a nap should be timed to obtain the maximum ben- efit. This will vary depending on circumstances, but in general the following guidelines are applicable: • Napping for longer periods (2+ h) before the start of a night shift can prevent fatigue for extended periods (e.g., through a night shift) and can be very beneficial (Dinges et al. 1987). • Napping for short periods (less than 30 min) may result in subjective alertness (Tietzel and Lack 2001) but little is known about how long this effect provides actual benefits. • Individuals who are day-oriented and not sleep-deprived avoid napping during the hours of 6:00 and 10:00 p.m., approximately, when alertness is usually high (the so-called wake maintenance zone). • Schedule a nap during the mid-afternoon (1:00 to 3:00 p.m.) when alertness is low. • Allow 15 to 30 min after a nap to become fully alert. The deeper the sleep the longer the period needed to become fully alert. 2.2 Effectiveness Napping as a defensive measure reduces fatigue in the work period approximately in proportion to the duration of the nap (Mollicone et al. 2008). Further, the timing of the nap in relation to the work period is important, such that a nap closer to the work period is generally more effective. 2.3 Highway Construction Environment Implementation As with the preventive measure of adequate sleep, defensive napping is a matter of individual worker knowledge and the opportunity to act on that knowledge in advance of experienc- ing fatigue. The latter aspect is related to work schedule man- agement, notification of shift change, and providing sufficient advance notice to allow workers to use the time available to them to adjust through napping. In practice, the construction companies the team interviewed attempt to give at least a day off prior to switching from day to night shift. 3. Good Sleeping environment A good sleeping environment sets the stage for restorative sleep. Type of Countermeasure: Preventive 3.1 Basis Although most people can get used to almost any sleep environment, especially when they are exhausted, certain

95 characteristics of where an individual sleeps can enhance or compromise how restorative a rest period is. To ensure that sleep is restorative, sleeping environments must be quiet, dark, and comfortable. To ensure a quiet environment, the individual should remove any noise sources, especially those that are unpredictable (e.g., pets in the bedroom). Use of earplugs to reduce traffic noise or other external sounds helps many people, as well as the use of a constant low-level noise source such as a fan. The amount of light in a sleeping area can be reduced by using black-out shades, heavy dark fabric for curtains, or “hurricane shutters” over windows. Some people also use eyeshades in areas where there is substantial light leakage. Comfort in the sleeping environment is related to the qual- ity of the bed and the temperature. The bed and pillows should be of appropriate firmness for personal comfort and the temperature not too warm or too cold by personal preference. Two additional environmental recommendations include orienting the clock face away so as not to worry about the time, especially when having difficulty falling asleep, and using the sleeping area only for sleeping—not other arousing activities such as work or watching TV and videos. There may be practical limitations to controlling the physical elements of the sleep environment, especially when traveling. For example, some hotels do not provide room- darkening shades, or outside traffic noise may be unavoid- able. However, an individual can prepare for some of these factors by carrying earplugs and eyeshades. It is also impor- tant to not invest too much psychologically in the need for certain sleep environment characteristics because this can lead to insomnia. 3.2 Effectiveness The principal advantage to using this countermeasure is that an individual can adapt their sleep environment to meet indi- vidual needs and have a continuing positive effect on sleep quality. 3.3 Highway Construction Environment Implementation The importance of sleep environment characteristics is pri- marily an educational issue. The fact that sleep hygiene prin- ciples are routinely suggested to individuals seeking sleep medicine consultation indicates the need for continuing edu- cation of workforces that may be subject to sleep disruptions. This can also include information to help modify family rou- tines modification in order to facilitate sleep for the affected individual. 4. Limiting Overtime and/or Work Schedule Modification Type of Countermeasure: Preventive 4.1 Basis Evidence suggests that longer duration shifts and overtime are associated with increased incidence of error and safety- related incidents (Åkerstedt et al. 2002). The reasons for this are complex, involving a combination of effects that lead to reduced performance with increasing time on task, neurobiological processes leading to increased homeostatic pressure for sleep, and possibly a generalized lowering of risk tolerance at particular points in the work cycle (otherwise known as “complacency”). The principal choices in limiting overtime or modifying the work schedule involve how long the shift will run, what time it will start, and which workers to assign. Hours-of-service (HOS) rules for transportation industries tend to limit the overall amount of work time, by specifying how long, for example, commercial drivers may spend behind the wheel. Alternative approaches to scheduling in the medical profes- sion involve reducing the number of work hours for interns from over 80 per week to 60 per week. Similarly, HOS rules specify the maximum number of hours per day for certain professions (e.g., nuclear power plant operators); the minimal period between shifts, such as 10 h; and a minimum period off following a number of consecutive days of work. Later starting times appear to be associated with lower risk (Folkard and Åkerstedt 2004), and the prior schedule of the workers needs to be considered. For example, workers who have become adapted to afternoon shift work would be better able to adapt to night-shift start times than to rotate “backwards” to a morning start (Moog and Hildebrandt 1987). Most of the research in this area is specific to a particular work environment, although risk modeling studies have iden- tified common patterns across different working environments suggesting that shorter shifts are associated with lower risk. This must be balanced against the requirements of the work environment, and longer shifts (e.g., 12 h) may be acceptable if only a few are worked in succession (Åkerstedt 1998). 4.2 Effectiveness Limiting work hours and work schedule modifications are associated with increased worker satisfaction and reduced inci- dence of errors on the job, by providing more time for sleep. These findings are sufficiently well-documented that they are the basis for various HOS rules mandated by the federal gov- ernment and underlie various schedule analysis and modeling tools under development by the research community.

96 4.3 Highway Construction Environment Implementation Implementation of this countermeasure in the rapid renewal highway construction environment involves a number of considerations. First, there appear to be only two basic shift ranges in the projects the team evaluated: day work (approxi- mately 7:00 a.m. to 5:00 p.m.) and night work (approximately 7:00 p.m. to 5:00 a.m.). These schedules seem to be a blend of traditional work hours during the day and the need to accom- modate late afternoon rush-hour traffic in the evening and be done by early morning. Thus, there are fairly rigid parameters associated with start and stop times that do not easily accom- modate change. Work scheduling during “regular” shifts, either day or night, appear to currently operate on the basis of project labor agreements (PLAs) for union states and common practice in non-union states. In either case, the usual approach to sched- uling involves either 8- or 10-h shifts, with a maximum of a 55-h week. The usual minimum time off between consecutive work periods is 1.5 days. Based on the team’s observations of projects, the aspect of rapid renewal construction work that can most benefit from limitation of work hours or schedule modification is the practice of continuous weekend closures. These closures tend to run from 11:00 p.m. Friday evening to 5:00 a.m. Monday morning and are associated with considerable sleep disrup- tion among managers and, possibly, laborers. Current prac- tice on accelerated projects is to continue using the same workforce for another week of standard day or night work schedules following a weekend closure. The team’s data sug- gest that workers show high levels of fatigue following this type of closure and resumption of a standard schedule. A simple modification to this practice is to provide workers Monday off following a weekend closure or at least to imple- ment a later start time. The trade-off involves less work accomplished on that Monday, but this may still be a benefi- cial trade-off for the lower productivity expected of fatigued workers. 5. Fatigue education Type of Countermeasure: Preventive/Operational 5.1 Basis An understanding of the fundamental nature of sleep loss, circadian rhythm, fatigue, performance impacts and amelio- ration strategies is a key element of both preventive and oper- ational approaches to reducing fatigue. Education and training formed the basis of the highly successful NASA fatigue countermeasures program and over time led to a fundamental change in culture and philosophy regarding fatigue, both at the worker and management level. Education is a basic ele- ment of current approaches to fatigue risk management sys- tems, and can help to overcome widely held misconceptions about the nature of the problem and ways to deal with it. Key points to address in educational programs include the following (Caldwell et al., 2008): • In the long run, there is no substitute for sleep. • Fatigue is based on physiological mechanisms and cannot be overcome by motivation or willpower. • Self-assessment is unreliable and potentially biased by work circumstances. • Individuals vary in sleep need and responses to sleep loss, and responses are difficult to predict on a case-by-case basis. • There is no “one-size-fits-all” solution. • There are ways to prevent and mitigate fatigue, but they must be properly employed. • Fatigue has safety, well-being, and economic consequences. 5.2 Effectiveness Although training is sometimes considered a weak response to structural, organizational problems such as fatigue, it is a necessary first step in gaining commitment at the individual and corporate level to address the problem. Simply having an educational program is no guarantee of results, and some studies suggest that knowledge decays rapidly, while others indicate that higher levels of corporate commitment and engagement lead to longer lasting impressions. 5.3 Highway Construction Environment Implementation While important as a fundamental component in fatigue management, translation of existing scientific knowledge into usable programs for employers and workers is not straight- forward. The team’s interviews with management SMEs sug- gested that fatigue is a topic of concern, and that there is some coverage of the topic in company safety training. However, the interviews yielded no material that would allow us to assess the quantity or quality of the training. The single source the team reviewed, “toolbox talks,” yielded some relatively cursory material that was not contextualized to the rapid renewal environment. Educational programs could be imported and adapted from transportation industries such as commercial aviation. Comprehensive and contextualized training about fatigue for the rapid renewal environment will need to address the spe- cific risk factors and operational constraints of the work domain. These include long shifts, occasional double shifts, rapid switch to night work from day work, and continuous

97 weekend closure effects upon sleep opportunity. At the pres- ent time there are no standards to guide contractors in their selection of consultants or material for fatigue training, nor is there a well-developed information dissemination path- way. This may be an appropriate role for industry association groups, which have established training material and guid- ance for other areas of safety concern. 6. napping Type of Countermeasure: Operational 6.1 Basis Using napping as an operational fatigue countermeasure involves sleeping for brief periods during the work shift. It is important to consider the following: • Where to take the nap? • When to take the nap? • How long to nap? These questions will have different answers depending on the nature of the work. The guidelines described for “defen- sive napping” are also applicable to napping during work periods, appropriately adapted. In general the following guidelines specific to workplace napping are applicable: • Taking 10- to 12-min “power naps” almost anytime as needed and appropriate can help refresh an individual for a short period of time. • Being aware of the potential effects of sleep inertia follow- ing the nap and counteracting them with caffeine if necessary. • Using napping as part of a continuous, nonsplit shift duty period and not using it to extend the duty period. There may be times when workers feel overwhelmed by sleepiness despite “defensive naps” or a sufficient sleep period before work. In this case, they should take an “emergency nap” of 15 to 30 min as soon as the work activity permits. 6.2 Effectiveness Naps of 20 to 30 min during appropriate periods of a work shift have been shown to improve performance and subjec- tive alertness during the subsequent work period. Studies of extended shifts (16 h) have included naps of up to 2 h, although this has entailed more sleep inertia and potential interference with recovery sleep during the off-work period. 6.3 Highway Construction Environment Implementation Implementing on-shift napping in a highway construction environment may be a considerable challenge. The team’s field studies suggest that some workers do take naps during their lunch breaks or other times when it is appropriate, and they tend to use their personal vehicles as the location for napping. Due to the safety-critical nature of construction, workers must be very cautious about where and when they take breaks, particularly if they are asleep for a brief period. Personal vehicles as a location for napping are probably rela- tively safe, although ultimately it would be desirable to opti- mize the conditions under which naps are taken, in order to avoid excessive noise, vibration, overheated vehicles from sun exposure, and potential contact with construction equipment. While there may be a larger percentage of nappers than are actually reporting on the survey, the issue is one that will ulti- mately require organizational commitment to be anything other than an informal, ad-hoc measure, which may result in disciplinary consequences. Management consensus from the team’s field surveys was that napping during work was not acceptable, with a few exceptions. 7. Caffeine Alertness can be increased by consuming caffeine in the form of coffee, tea, soft drinks, chocolate, caffeine gum, or non- prescription caffeine tablets (Table C.2.). Type of Countermeasure: Operational Table C.2. Caffeine Content from Various Sources Percolated Coffeea 140 mg/7 oz Brewed Coffee 80–135 mg/7 oz Red Bull Energy Drink 115 mg/12 oz Jolt Cola 72 mg/12 oz Coca-Cola 34 mg/12 oz Tea 70 mg/6 oz Chocolate 5-35 mg/1 oz No-Doz or Vivarin 200 mg/tablet Excedrin 65 mg/tablet Dristan 30 mg/tablet a The caffeine content of coffee has been shown to vary considerably so this value should only be considered a general guide.

98 7.1 Basis Caffeine is one of the most commonly used fatigue counter- measures, usually obtained through a cup of coffee. Other popular drinks and foods contain a lot of caffeine, including cola drinks, chocolate, and tea. Numerous medications also contain caffeine, as do “alertness aids” such as No-Doz and Vivarin. Caffeine is widely available, and taking a brief break to take caffeine can have the additional advantage of breaking up a tiring work routine. Caffeine affects the nervous system within 15 to 20 min, depending on mode of ingestion. The effects include a more rapid heartbeat and increased alertness, and they last for about 4 to 5 h, but may last up to 10 h in especially sensitive individuals. It is important to use caffeine only as a short-term way to boost alertness; regular use can lead to tolerance and various undesirable side effects, including insomnia and disrupted sleep if taken too close to bedtime. Here are some situations where using caffeine makes sense: • In the middle of a night shift (especially on the 1st and 2nd day of the work week when circadian disruption tends to be most pronounced and alertness most compromised). • Mid-afternoon when the post-lunch alertness dip is greater because the individual did not get enough sleep. • Prior to an early morning commute following a night shift, but not within 4 h of going to sleep if the individual is sensitive to sleep disruption from caffeine. • Prior to a brief nap of 15 to 30 min, to reduce the effects of sleep inertia from the nap. Caffeine effects will become active as the nap is ending. It is always best to try to reduce fatigue through obtaining enough sleep, but when this doesn’t happen and boosting alertness for a period of several hours is needed, using caf- feine makes sense. Caffeine will affect sleep and should not be consumed 4 to 5 h prior to sleep, unless the individual is not sensitive to caf- feine disruption of sleep. Caffeine in the body will make fall- ing asleep more difficult, reduce sleep length, and disrupt the quality of sleep. Our brains gradually build up a tolerance to repeated con- sumption of high levels of caffeine (e.g., five or more cups of coffee per day). A frequent coffee drinker needs a higher dose of caffeine to obtain the same “boost” effect of the more casual coffee drinker. Caffeine should be consumed sparingly, to “save the boost effect” for when it is really needed. That is, plan to use caffeine in the middle of the afternoon dip (1:30 to 3:30 p.m.) or, if working through the night, use it after midnight during the circadian low point. 7.2 Effectiveness The alertness enhancing effects of caffeine have been well documented, and performance is increased on various mea- sures when caffeine is used, particularly if people are sleep- deprived. There are, however, considerable individual differences in the effectiveness of caffeine. The duration of the effects is sufficient to counteract moderate levels of fatigue, when taken in time periods when fatigue will be a problem. Further, some putative sources of “energy,” such as high sugar colas and energy drinks, are lower in caffeine per fluid volume than coffee, and tend not to have the same alert- ing effects as drinks with higher amounts of caffeine. 7.3 Highway Construction Environment Implementation This countermeasure appears to be well-implemented on an individualized and informal basis in highway construction environments. Workers report either bringing their own caffeinated beverages to the job site or being able to obtain caffeinated beverages near the work site. Contractors may also consider providing coffee or other caffeinated beverages at a central location to the work site, for example, in the work site office, or at the location where gathering for “stretch and flex” safety meetings are held. 8. Anchor Sleep Type of Countermeasure: Operational 8.1 Basis Anchor sleep (or “split sleep”) refers to a regular sleep period of at least 4 h, obtained at the same time each day. The anchor sleep period is supplemented by an additional sleep period taken when the schedule allows. Some work schedules do not allow a full 8 h of sleep at the same time period every day. In order to effectively cope with schedules like these, workers should arrange to get at least 4 h of sleep at the same time every day; additional sleep can be obtained as the schedule permits. Anchor sleep periods have the advantage of stabilizing the circadian rhythm to a 24-h period, so that workers will not constantly feel “out of sync.” The anchor sleep period should be timed so that circadian rhythm high and low points cor- respond to work and sleep periods. Anchor sleep is not a substitute for getting a full 8 h during any 24-h period. Instead, it is a coping mechanism meant to keep an individual’s circadian rhythm synchronized to his or her daily schedule, by allowing sleep for a period of time when sleep is possible. It is important to supplement anchor

99 sleep with supplemental naps that are sufficient to provide the complete sleep allotment needed on a daily basis. This countermeasure is helpful because it anchors the sleep cycle. Research data indicate that it is important to have the anchor sleep period occur at a constant time every day. It is important to try to time the main or supplemental sleep epi- sodes so that they do not coincide with circadian “forbidden zones” (wake maintenance zones) where initiation of sleep would be difficult—typically these times are approximately 8:00 a.m. to noon. (when not sleep deprived) and particularly 6:00 to 10:00 p.m. Meals should be taken at the times that workers normally eat. When taking supplemental sleep, it is important that it not be too close to the anchor sleep period, or interference will occur. Caffeine consumption should be moderated during the use of anchor sleep as well, since the effects of caffeine last for about 5 h, and may interfere with either the anchor sleep period or the supplemental sleep in individuals sensitive to this effect. Anchor sleep should be used as a coping mechanism for situations where a worker cannot get a full 8 h of sleep, but not as a routine. While split sleep periods may provide a suf- ficient amount on a short-term basis, getting a sleep allot- ment in a single episode is preferred. 8.2 Effectiveness Laboratory studies of anchor sleep and split sleep periods indicate that performance tends to be maintained at levels equivalent to getting a consolidated sleep period. It is not known if performance stability is maintained over weeks to months on such schedules. 8.3 Highway Construction Environment Implementation Use of anchor or split-sleep schedules would seem most appropriate for highway construction workers who are work- ing on continuous closure operations, particularly manage- ment personnel who are not covered by a specific labor agreement for daily work hours. An example would be a man- ager who wishes to be present at the start of a closure on Friday evening, and work as much as possible through the following Monday morning. An anchor sleep strategy for this individual would be to nap in the mid-to-late afternoon on Friday in preparation for staying up all night starting late Friday night. The manager could then return home to sleep early Saturday morning and probably get about 4 h of sleep. The manager could return to the work site for several hours, then take another long supplemental sleep in the mid-to-late afternoon. This process would be repeated until the end of the closure on Monday morning. 9. exercise Type of Countermeasure: Preventive/Operational 9.1 Basis Physical exercise has the principal benefit of improving over- all cardiovascular health and muscle tone. Additionally, regu- lar exercise improves sleep; individuals fall asleep quicker and sleep more soundly depending on the timing and the type of exercise. Exercise also enhances feelings of alertness for a short period. Physical exercise can also be used to reduce the feeling of fatigue resulting from not getting enough sleep. Research indi- cates that brief periods of exercise can reduce feelings of sleep- iness, although job performance does not improve. In rested individuals, a morning exercise break may improve alertness and driving performance for a brief period afterwards. The health benefits of regular physical exercise are clearly established, and individuals should consider initiating a regu- lar program of exercise or maintaining what they are already doing. If they work irregular hours or in situations that limit what they can do (e.g., no ready access to a gym; darkness), planning ahead and using alternative activities such as walk- ing can maintain a healthy activity level. Regular exercise will contribute to feelings of increased energy, by helping develop stamina and improving sleep. It should be a regular part of a healthy lifestyle. While exercise will promote health and improve an individ- ual’s sleep, it does not permit them to cut back on primary sleep. Exercise can reduce immediate feelings of fatigue resulting from schedule changes and sleep deprivation, but that feeling only lasts for about 30 min. The effects of exercise on job performance are complex, and tend to wear off quickly, pos- sibly even making performance worse in the afternoon. So, while an individual may feel better after exercising during a sleepy period on the job, they are still fatigued and should be aware that performance is likely to be compromised. Do not exercise too close to bedtime, because increases in body temperature and alertness may make it difficult to go to sleep. 9.2 Effectiveness Exercise as a fatigue countermeasure should be used primar- ily to develop cardiovascular health and to promote healthy sleep. As such, exercise is a complementary countermeasure and can facilitate the primary goal of getting adequate sleep. Exercise can be used as a very short-term countermeasure for brief enhancement of alertness, but the effects may not trans- fer to actual performance and will not last throughout the work period.

100 9.3 Highway Construction Environment Implementation Implementation of this countermeasure in the highway construction environment as a preventive countermeasure may be promoted through the regular use of morning safety meetings and “stretch and flex” exercises that are part of this routine. It is common practice with some contractors to hold these crew-mustering meetings before starting work, to discuss recent safety concerns and to promote physical warm-up. These meetings could also be used as a platform for promoting regular exercise in the off-work hours to enhance health, restorative sleep, and general alertness. However, it should be borne in mind that well- intentioned advice to get up early to exercise is counterpro- ductive for fatigue management if arising early curtails the sleep period. 10. diet This countermeasure involves varying meal content in order to increase alertness or promote sleep. Type of Countermeasure: Preventive 10.1 Basis The physical activity associated with eating can itself induce an alerting effect; however, current research evidence suggests that specific food content has little, if any, impact on level of alertness or feelings of sleepiness. An attempt to extend an individual’s endurance or pro- mote sleep by altering the content of meals is unlikely to suc- ceed. It is better to focus on consuming a nutritionally healthy and balanced diet at the appropriate times of day. Getting a balanced, nutritious diet at appropriate times is often difficult for shift workers. Schedules often limit eating to what is available when time and work permit. Individuals can avoid this situation with appropriate plan- ning. Packing meals prior to leaving home, taking breaks where supermarkets are located, and take-out meals from (non-fast-food) restaurants are some steps that can be taken to make sure the right foods are available when needed. Whenever possible, individuals should try to eat meals at times that correspond to their normal meal times; this will help maintain a regular sleep-wake cycle, since meals are a time cue that influences circadian rhythms. Conversely, the gastrointestinal system will process food best when it is eaten at the right times of day. One of the primary complaints of shift workers is gastrointestinal discomfort caused by being forced to eat at night when the body is not optimally prepared to handle the food intake. Consuming large meals prior to sleep can disrupt the subsequent sleep period and also result in gastrointestinal discomfort. 10.2 Effectiveness Eating properly is a key element of overall general health, which can contribute to quality and quantity of sleep. Eating or drinking specific foods or beverages (other than caffeine) for alertness enhancement is unlikely to work. 10.3 Highway Construction Environment Implementation Good dietary habits and meal content could be part of an overall fatigue, health, and wellness training program for highway construction workers. There are no specific recom- mendations for dietary content for workers in this domain. 11. Rest Breaks Rest breaks from the performance of a work task can reduce the effects of sleep loss for a short time. Type of Countermeasure: Operational 11.1 Basis Research studies have demonstrated that people who are sleep deprived or work on continuous but monotonous tasks during the night show degradations in their performance. However, if they take breaks, sometimes as short as 7 min, the degraded performance is reduced and they also report feeling better. The effects of rest breaks last only for 15 to 25 min, but this can be very important during critical tasks that are safety sensitive. The break does not have to involve napping but simply a change in activity, such as stopping whatever task the worker is currently engaged in, walking around, stretching, talking to others, and so forth. The breaks may have more impact on fatigue later in the work cycle. An additional benefit of rest breaks is that they temporar- ily remove workers from the work site and thus from poten- tial risks. 11.2 Effectiveness Rest breaks can provide temporary (15 to 25 min) relief from performance declines and subjective fatigue due to sleep loss. They are a short-term measure and not a substitute for adequate sleep.

101 11.3 Highway Construction Environment Implementation Most highway construction jobs have some degree of self- paced structure, which would allow workers to take breaks when needed. There are certain multiperson, time-intensive tasks, such as pavement finishing, that would not be condu- cive to individual decisions to take a break, but with team support rest periods could be agreed upon. Rest periods for “work to completion” kinds of tasks should be considered by construction superintendents and planned for on the basis of when fatigue is likely to be a problem, such as toward the middle or end of a night shift or closure period, or to break up a monotonous or physically demanding task. 12. Temperature and Ventilation This countermeasure involves changing airflow and tempera- ture in the surrounding environment to increase alertness. Type of Countermeasure: Operational 12.1 Basis Altering the airflow and temperature in the surrounding envi- ronment is fairly easy for most workers, through control of air conditioning or increasing fresh air by opening a window. It is important to ensure that the air quality in the immedi- ate operational environment is good, since fatigue is one of the symptoms often associated with impurities in the air. The fatigue that results from impurities can be a physiological reac- tion to reduced oxygen, and is an indication that the environ- ment should be changed. For highway construction workers, air impurities might result from improperly ventilated exhaust systems or fumes from construction material such as asphalt. Temperature tends to affect alertness indirectly, by chang- ing the overall comfort level. If an individual is inclined to feel sleepy anyway, a warm environment may increase those feel- ings. However, the opposite is not true: there is little benefit to opening a window or lowering the temperature if an indi- vidual is already fatigued. While there may be a brief effect of lowering the surround- ing temperature or increasing airflow, research data suggest that the impact is very short and not likely to increase alert- ness for longer than a few moments. So, if an individual is feeling sleepy, it is best to use another countermeasure. 12.2 Effectiveness Changing temperature or ventilation may enhance alertness, momentarily, but it is not an enduring effect and should not be considered a practical countermeasure. 12.3 Highway Construction Environment Implementation Given the only momentary effects of changing temperature or ventilation, use of this countermeasure in the construction environment should be limited to supplementing short term other countermeasures, such as rest breaks or exercise. 13. Self- and peer-Monitoring Use of observational data to assess levels of fatigue in self or co-workers. Type of Countermeasure: Operational 13.1 Basis Performance impairment does not necessarily indicate fatigue, and self-report of fatigue does not necessarily indicate per- formance impairment, but the likelihood of either is increased in the presence of the other. For these reasons, it is important that workers pay attention to their own subjective state, as well as monitoring the quality of their work. There are various rules of thumb that workers can use to self-monitor, including knowledge of their prior sleep-wake patterns; overt symptoms such as yawning, drooping eyelids, “catching” themselves falling into microsleeps; and feelings such as “fighting sleep”—items also featured in one of the most frequently used fatigue rating scales. Research has shown that people are aware of their fatigue as it is developing and influencing their performance, includ- ing safety incidents, and that this awareness is strongly correlated with physiological measures of fatigue such as brain-wave measurements. The self-awareness of fatigue state needs to be linked to knowledge of proper actions (such as taking a break), so that people will not try to fight fatigue with relatively ineffective countermeasures. However, it is also known that fatigue impairs judgment and self-regulation, and so self-observation and report should not be relied upon exclusively. Fatigue involves subjective feelings of tiredness, behavioral patterns of taking shortcuts and omissions, and a basis of physiology. Technological measures and most self-report rating scales of sleepiness or alertness tend to focus on the single dimension of momentary alertness. A more compre- hensive representation of fatigue needs to address a broader range of underlying factors. This is important because not all jobs, workers, and tasks are the same, and they may be dif- ferentially vulnerable to different fatigue risk factors. Observation of worker behavior by peers or supervisors relies on the observer’s ability to distinguish specific behav- ioral characteristics indicative of impairment. There is very little applicable literature in this area concerning fatigue. A

102 variety of symptom checklists have been employed by researchers, primarily as adjuncts to primary methods such as physiological or self-report measures. The checklists include facial markers such as eye closure, loss of facial muscle tone, and so forth as a basis for determining likely state of alertness. As with all such measures, these behaviors may occur without necessarily indicating an underlying state of fatigue, or the state of fatigue may be momentary. Vice versa, fatigue may be present without the overt symptoms, or with the overt symptoms occurring only occasionally and, there- fore, being difficult to observe. The successful use of observa- tional approaches depends on the ability of the observer to distinguish “normal” behaviors from those clearly indicative of impairment and to be able to do so on a near-continuous basis because fatigue is a dynamically changing state. This makes peer or supervisor observation an unreliable method for detecting fatigue. That said, workers should be encour- aged to alert others when observing potentially fatigue- related behaviors, as the likelihood that fatigue is actually present is high when the symptoms are readily noticeable. 13.2 Effectiveness Research indicates that individuals can reliably self-assess their own momentary state of fatigue, and less reliably assess others. The overall effectiveness of this approach depends on knowledge and ability to act on the assessment of fatigue. This becomes a matter of implementation. 13.3 Highway Construction Environment Implementation The team’s interviews with construction superintendents suggested that they have certain rules of thumb for determin- ing when their crews are fatigued, including observation of erratic performance, facial characteristics, and irritability as well as knowledge of their prior schedule. Superintendents also state that they are aware of which individuals are more likely to be able to work certain hours and schedules, and of different individuals’ propensity to fatigue. They construct schedules and assignments, to the extent they are able, on the basis of that knowledge. These findings suggest that supervisory monitoring is already taking place, albeit on an informal basis. The team did not find any evidence that individual workers were encour- aged to self-monitor and self-report, or that there were any formal or informal means to act on individual reports. All construction companies stressed that workers are encouraged to take hydration breaks whenever necessary. The results indicate that there may be a role for approaches to “fatigue-proofing” highway construction environments through a combination of training on fatigue effects how to recognize them and more clearly establishing criteria for rec- ognizing fatigue on the job and what to do about it. Examples from other work environments include using more humor and joking around on the night shift to see how people respond, and those showing unusually low response or irritability (com- pared to their usual personalities) would be watched or backed up more closely in safety critical tasks. 14. Hypnotics or Stimulants Type of Countermeasure: Preventive 14.1 Basis This countermeasure involves the use of synthetic or natural drugs to promote sleep when schedule changes interfere with falling asleep, or the use of synthetic or natural drugs to reduce the effects of sleep loss and enhance alertness under condi- tions of fatigue. Hypnotics If workers have a sudden change of schedule that interferes with their ability to go to sleep, there are drugs and herbal substances that can be used to promote sleep. Hypnotic drugs such as Ambien are part of a class of drugs that are useful for inducing sleep. These drugs reduce the amount of time required to fall asleep, improve ability to stay asleep, and can maintain sleep for 7 to 8 h. Herbal remedies such as Valerian root, chamomile, kava, and lavender are promoted as sleep aids, but the evidence for their effectiveness is much less clear. Sedatives and hypnotics have the advantage of being appli- cable to a number of situations that might interfere with sleep, such as shift changes, jet lag, or stress-related short-term insom- nia. The drugs can help to alleviate these short-term problems and be discontinued to preclude the risk of dependency. Depending on the specific type of drug class, there are changes in the nature of an individual’s sleep although the significance of these changes is unknown. It is possible to develop a dependence on hypnotics if used for a long period of time, and there is often a “rebound insomnia” in which sleep is slightly worse for one or two nights after discontinuing the drug even if used for only short periods of time. If the drug is a particularly long-acting one, or if the indi- vidual has high sensitivity, there may be a “hangover” effect the next day where the individual may feel sluggish or show sleep inertia. Sleep inertia or actual inability to wake up while on hypnotics largely precludes their use during operations. Hypnotics should be used only by prescription from a phy- sician, and only for as long as necessary to “get over the hump”

103 of sleeplessness, and this should be at the lowest clinically indicated dose for as short a time as possible. Hypnotics are an aid to achieve sleep schedule re-adjustment, not a pre- ferred means for getting sleep over the long run. Stimulants Stimulants exert a physiological effect on the nervous system so that the effects of sleep loss can be temporarily reduced. Caffeine (discussed in a separate entry) is an example of a stimulant—one that does not require a prescription and that does not have any significant adverse side effects unless con- sumed in very large quantities. Stimulants are particularly useful to the relatively small population of individuals who suffer from narcolepsy or other debilitating sleep disorders. Military personnel some- times use stimulants during sustained operations, under con- trolled conditions, and supervised by a flight surgeon. The effects of prescription stimulants such as dextro- amphetamine and modafinil are clear-cut: Alertness is increased and performance is enhanced, relative to sleep-deprived indi- viduals. These effects are also observed to some extent with a number of over-the-counter decongestants containing pseudo- ephedrine, and with herbal stimulants such as ephedra. Synthetic stimulants such as amphetamine and modafinil are controlled substances and should only be used under the guidance of a physician for treatment of a specifically debili- tating sleep disorder. Herbal stimulants are unregulated, and the effects of many are unknown because of lack of proper evaluation. However, it is known that ephedra, in particular, is associated with heart attack and stroke, and it is likely to be controlled soon. All herbal stimulants should be considered as unproven and a safety hazard. Decongestants are not designed for increasing alertness—this happens as a side effect, along with increased drying of mucous membranes. Even under the guidance of a physician, stimulants can have unwanted and potentially dangerous side effects, including changes in blood pressure and pulse, headaches, irritability, appetite loss, insomnia, nervousness, talkativeness, and sweat- ing. Extreme reactions include hallucinations and paranoid psychosis. Prescription stimulants are not generally permitted in oper- ation of public transportation vehicles in the U.S. and many other industrialized nations. Randomized drug testing is regu- larly carried out to cut down on the usage of most known stimulants, at the threat of loss of job. These prohibitions may also apply to certain job categories in highway construction. Most stimulants have a high potential for addiction and abuse because of the rapid euphoria that results from high doses. This can lead to a cycle of binging and crashing, and long-term abuse can lead to mental and behavioral disorders. Finally, possession and use of controlled substances with- out a proper physician’s prescription is illegal and can result in fines and jail time. 14.2 Effectiveness Hypnotics and stimulants have demonstrated effects on sleep and alertness. Due to the controlled nature of these sub- stances and the potential for legal problems and abuse, the team does not recommend systematic application in the highway construction environment. 14.3 Highway Construction Environment Implementation Discussion of hypnotics and stimulants is usually a part of fatigue training in other domains, when discussed in con- junction with medical issues such as sleep disorder screening. Individuals should be encouraged to seek sleep disorder screening if they believe they have a problem or if manage- ment notices specific fatigue-related job performance issues. 15. Model-Based Schedule Optimization This countermeasure involves using the knowledge of physio- logical processes controlling sleep and alertness to predict worker level of fatigue on the job. Type of Countermeasure: Preventive 15.1 Basis Research indicates that level of alertness at any particular point in time is controlled by three basic factors: (1) circadian rhythm, (2) prior sleep and wake history, and (3) length of time awake. Specific alertness values can be predicted from knowing where an individual is in their circadian phase, when and how long they slept during the last few days, and how long it has been since they woke up most recently. This conceptualization conforms to biology and common sense: An individual is naturally sleepy toward the late evening hours, sleeping recovers alertness, and alertness decreases the longer an individual is awake. It is possible to use the general nature of these models to predict how an individual is likely to be feeling during a sched- ule change and through continued schedules such as night shifts and weekend closures. For example, if a worker is going to switch from day to night shifts, it is likely that he will wake up on the first day of the night shift at his usual time, such as 7:00 a.m. By the time he goes to work at 11:00 p.m., his alert- ness profile will be at the circadian high point, making it

104 initially easier to stay awake, even though he would be habitu- ally going to bed at this time. As he stays awake throughout the night, his alertness will decrease as it follows the circadian rhythm process. There will be no increased value on his sleep recovery process to balance that out, and the recovery sleep that is obtained will be curtailed because it is during the day. Using knowledge of how alertness is affected by internal physiology can help individual workers and schedule plan- ners to anticipate how fatigue crews will be at certain points in time, and to think about other potential countermeasures they might use, such as caffeine, a nap, or to the extent pos- sible, schedule adjustments that will promote adaptation. Alertness models are useful to estimate periods of reduced alertness so that specific countermeasures can be identified and used. Additionally, alertness profiles from the models can be used to design fatigue-friendly work schedules. It is important to recognize that there are many other vari- ables contributing to momentary alertness levels, such as stimu- lation level, other countermeasures employed, and individual differences in sleep need. Therefore, model predictions should be used as guidelines rather than as indicators of absolute pre- dictions of alertness. This is not really a limitation; model pre- dictions can effectively be used to compare different schedule options to see which is the most fatigue-friendly option and to identify the best times to deploy fatigue countermeasures. Research with application of models in specific industrial settings has shown that there tends to be resistance to adopting model recommendations, which is predominantly due to a lack of training in how to interpret model predictions correctly. Models, like other tools, should be used with proper training on their inputs, interpretation of results, and appropriate uses. This training does not need to involve a major time commit- ment but without any training model predictions can be misunderstood, leading to bad scheduling or countermeasure decisions, and subsequent distrust of the modeling tool. 15.2 Effectiveness Fatigue models are effective for providing estimates of risk of impairment under various schedules, can guide countermea- sure application and timing, and can serve as an educational tool for understanding fatigue and its impacts. The limited evaluations of fatigue modeling in operational environments suggest that adoption and diffusion are limited at this time, and that organizational and work practice barriers may impede broad adoption. 15.3 Highway Construction Environment Implementation Findings from the team’s interviews with managers and superintendents in construction companies suggest that scheduling tools are used, but primarily by designers and engineers to develop task sequences for construction and for contractual compensation. Even the largest projects the team observed appear to be relatively “low-tech” when it comes to safety training and worker scheduling; they are performed more on the basis of standard practice and con- struction schedule needs than consideration of worker fatigue, although this does come into play over the long term. There is some prospect for combining fatigue model- ing with analysis and scheduling tools that are used for highway projects, such as Construction Analysis for Pave- ment Rehabilitation Strategies (CA4PRS). Construction projects that use software for worker scheduling could include fatigue prediction as an additional scheduling criterion at a relatively low investment cost, making model-based sched- ule optimization a promising technology for the near future. The team foresees that an industry association, such as Associated General Contractors (AGC), may champion such a modest investment as part of the development of Fatigue Risk Management Systems (FRMS), addressed in the next section. 16. Fatigue Risk Management System (FRMS) A comprehensive program for addressing worker fatigue that is a component of an overall safety management system. Type of Countermeasure: Preventive 16.1 Basis The concept of FRMS has evolved with the advances in fatigue science, modeling, and theories of organizational risk and error. Fundamentally, an FRMS is part of a “defense in depth” strategy for addressing a broad range of safety issues within an organization. FRMS are meant to be part of a safety culture and to provide a flexible means to address fatigue that is an alternative to prescriptive HOS rules. The fundamental elements of an FRMS are shown in Fig- ure C.1. Key elements of such a program include incident report- ing, including voluntary reports by workers and crew; moni- toring of fatigue related information (such as reports and safety trends); modeling and assessment of work schedules; and tracking of related information such as absenteeism. Education and training programs are a fundamental part, as is a steering committee of actively involved staff to keep the system functioning. FRMS have been implemented in a number of industries with round-the-clock operations, primarily transportation.

105 16.2 Effectiveness The effectiveness of FRMS is unknown, in terms of overall impact of fatigue-related safety problems. Evaluation data concerning education is mixed, and there is one study sug- gesting a positive trend of increased sleep in personnel participating in an alertness management program. Other evaluation studies report increased awareness of fatigue, but also problems related to organizational change/acceptance. There are no set criteria or regulatory standards for developing or evaluating FRMS program content or for monitoring effec- tiveness of implementation. Transport Canada, however, has developed extensive toolkits for FRMS development in trans- portation, which can be easily adopted for other settings. 16.3 Highway Construction Environment Implementation Given the range of contractors the team observed in this research—small and large, with projects ranging from mod- erate to very large—the team believes that full FRMS imple- mentation in the highway construction environment would be premature. Safety programs and training seem to be the province of a single individual even in the very large pro- grams, and the personnel or organizational infrastructure and the knowledge base for developing an FRMS, or for properly evaluating consultant offerings, does not appear to be available. Instead of moving to full FRMS at this point in time, the team recommends that contractors and states adopt a more practical approach to fatigue management by drawing on the various tools that are already available, such as training, coun- termeasures, and alertness modeling. These tools could initially be tailored to individual contractor needs, although the team foresees the prospect of an industry association, such as AGC, offering standardized materials and approaches that address the range of highway construction environments. 17. Worker Status Monitoring and Alerting Technologies Type of Countermeasure: Operational 17.1 Basis Alertness monitoring involves tracking the performance or physiological measures of workers to determine if they are approaching drowsiness or impairment. Operator status moni- tors seek to measure and record, in real time, some physical or physiological features of the operator’s eyes, face, head, heart, brain electrical activity, brain blood flow, muscular activity, reaction time, and so forth. Embedded measure tech- nologies compare current operator state on some aspect of performance on the task at hand, such as lane deviation or steering variability in a vehicle. Figure C.1. Elements of a Fatigue Risk Management System (FRMS). Adapted from Gander et al. 2011. Safety Management System • Based on culture • Collaborative • Proactive Fatigue Risk Management System Policy SteeringCommittee Education and Training Reporting Inputs • Incidents/Investigations • Voluntary fatigue reports Outputs • Work schedules for specific project phases • Personnel schedule rotations • Counter measure plans and implementation • Contract bidding and staffing strategies Analysis Inputs • Construction schedule requirements • Fatigue impacts of schedules • Counter measure effectiveness

106 Virtually all of these technologies are in the research stage. There is no research on how to best warn (alert) when a degraded state of impairment or drowsiness is detected. While some devices may be commercially available, there is not yet sufficient evidence about their reliability, validity, and effec- tive use to warrant routine implementation. Some of the questions that need to be answered include the following: • What are “normal” versus safety critical “abnormal” values for the measures generated by the device? • What constitutes acceptable performance for operators on a given task? Alternatively, are downward trends or gradual performance degradation seen? • Could a perfectly safe operator be classified as “unaccept- able” on occasions (e.g., score a false positive)? • What measures are best for providing an “early warning” so that operators have not already gone too far into the impairment zone? Suitable answers to these and other questions must be developed for each monitoring technology and for workers in each mode of operation. 17.2 Effectiveness Although some reliability has been shown in laboratory situ- ations, technological status monitoring for worker fatigue has not been effectively implemented in operational settings. Workers tend to find the technologies obtrusive. 17.3 Highway Construction Environment Implementation This approach does not yet warrant consideration for imple- mentation in the highway construction environment. 18. Bright Light or Melatonin for Circadian Shifting Type of Countermeasure: Operational 18.1 Basis The use of bright light as an operational fatigue counter- measure refers to timing the exposure to outside or bright indoor light in order to shift the circadian rhythm to corre- spond to a new work schedule or to acutely enhance alertness. Melatonin is a hormone produced by the pineal gland in the brain, which is secreted during the evening and night hours. Synthetic or natural melatonin is used in high doses to induce sleepiness, adjust the circadian rhythm to new sched- ules, or both. Bright Light One reason that shift workers are sleep-deprived is that their circadian rhythms do not adjust from that of a day-oriented worker because of the constant exposure to day-oriented time cues such as bright light and social activity. Bright light can be used in several ways to help overcome fatigue: • Bright light exposure in the evening shifts the circadian rhythm to a later time, such that maximum drive for alert- ness shifts from the evening to the night. • Bright light exposure in the early morning shifts the circa- dian rhythm to an earlier time, such that maximum drive for alertness shifts from the evening to the afternoon. • Day-to-day bright light exposure carefully adapted to the shifting circadian rhythm can result in further shifts to later or earlier times as desired. • Bright light exposure at any time of day also results in an acute alertness boost, which lasts as long as the light expo- sure continues. It should be evident that achieving the desired effect from bright light—to adapt to a new work schedule, for example— requires careful planning of the time of administration, knowledge of the present state of the circadian rhythm to fig- ure this out, and avoiding bright light at times when it is not supposed to be administered. In practice, therefore, only the acute alerting effect of bright light can be effectively achieved. There may, however, be side-effects of unintended circadian shifts, which may make it difficult to readjust to a normal schedule, for instance after a weekend closure with much nighttime bright light exposure. Using light exposure for several hours over a period of sev- eral days is usually most effective in shifting the circadian rhythm, although periods as short as 30 min have been shown to have an effect. The light exposure that will be most effective is in the range of 3,000 to 10,000 lux—much beyond that obtained simply from indoor lights—and blue light is espe- cially effective. Indoor light, however, also has the capacity to shift circadian rhythms if no bright light exposure is experi- enced, and the light sources typically used during road con- struction projects probably also have this capacity. Use of lighting to shift circadian rhythms or increase alertness may not be feasible in some work environments where night vision is required or where there is a need to maintain low light levels (e.g., cabs of equipment such as backhoes or loaders). Use of light exposure for resetting the circadian rhythm is a complex undertaking and should be guided by a person knowledgeable in circadian physiology. Additionally, the

107 benefits of resetting the circadian rhythm can be maintained only through fairly rigid adherence to the procedure, and ensuring that other time cues (e.g., daylight) are minimized. That is, in addition to light exposure, it is also important to control the timing of darkness. This is especially true for those workers who may be traveling between work and home in the bright morning sun. In these cases, it is important to mini- mize exposure to the sunlight by wearing dark glasses (special goggles are recommended). Melatonin Melatonin in pharmaceutical doses (0.3 to 5 mg) has fairly rapid sleep-inducing effects, and lowers alertness and body temperature following administration. When combined with proper timing and managed light exposure, melatonin can help to adjust the circadian rhythm to a new schedule by shifting the circadian rhythm. Like bright light, melatonin can be used in several ways to help overcome fatigue: • Melatonin administration in the evening shifts the circa- dian rhythm to an earlier time, such that maximum drive for sleep shifts from the night to the evening. • Melatonin administration in the morning shifts the circa- dian rhythm to a later time, such that maximum drive for sleep shifts from the night to the morning. • Day-to-day melatonin administration carefully adapted to the shifting circadian rhythm can result in further shifts to earlier or later times as desired. • Melatonin administration at a time of day when sleeping is normally difficult opens the gate for sleep. Note that the circadian rhythm-shifting effects of melato- nin work in the opposite direction as those of bright light. The timing of melatonin is an important factor; it needs to be taken in the proper relationship to the body’s biological rhythm in order to achieve the desired effect. Using melato- nin to delay the circadian rhythm is especially complicated because of the interaction with daylight, which is a more powerful adaptation mechanism. As with bright light, use of melatonin for resetting the circadian rhythm is a complex undertaking, and it should be guided by a person knowledge- able in circadian physiology. Additionally, the benefits of resetting the circadian rhythm can be maintained only through fairly rigid adherence to the procedure and ensuring that other time cues (e.g., daylight) are controlled. The Food and Drug Administration does not regulate the sale of melatonin, so the quality of products available in health food stores and other outlets is uncertain. Because use of melatonin can cause drowsiness, it should not be taken if an individual intends to drive or engage in other complex or potentially dangerous activity. The sleep inducing effects of melatonin are temporary, so while individuals may be able to get to sleep at an unusual time by using melatonin, they may not be able to stay asleep for as long as desired. Additionally, various side effects of melatonin have been reported, including worsened fatigue, depression, coronary artery constriction (possibly increasing heart attack risk), and possible effects on fertility. For these reasons, it is important to use melatonin only under the guid- ance of a properly trained physician. 18.2 Effectiveness Both bright light and melatonin have been shown, under proper circumstances, to facilitate re-adjustment of the circa- dian rhythm. Light also has an acute alerting effect which is, however, transient. These countermeasures are difficult to deploy effectively and reliably in an operational environment; thus, they are not considered effective for the highway con- struction environment. 18.3 Highway Construction Environment Implementation Bright light and melatonin are not recommended for use by highway construction contractors or state agencies. Individu- als may seek medical advice regarding their application, but they should not be generally promoted by the organization.