Nutritional Needs in Cold and High-Altitude Environments Applications for Military Personnel in Field Operations (1996) / Chapter Skim
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8 Military Schedules vs. Biological Clocks
8 Military Schedules vs. Biological Clocks
Pages 149-160
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From page 149... ...
~ r ~ A ^ = _ _ Coexisting with this military schedule are the inborn biological "clocks" that coordinate various physiological processes such as sleeping, eating, endocrine release, and motor activity. Long-term desynchronization of various physiological processes could result in disruption in the overall physiological ~ R
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From page 150... ...
The expressions of these biological clocks in such behaviors as feeding, body temperature, and motor activity are independent of environmental cues and can be considered as independent oscillators (Inouye and Kawamura, 19793. However, under normal conditions the activity of the circadian oscillator is entrained or synchronized by various environmental cues.
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From page 151... ...
While the light/darkness cycle and motor activity are just a few of many external cues that can alter circadian cycle, social factors may also play a role in synchronizing the clocks. Man is the only animal that habitually does not respond to his biological clocks.
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From page 152... ...
The effects of a decrease in core temperature have been reported elsewhere but it should be noted that hypothermia has major effects on a person's cognition and higher mental functions, resulting in amnesia, apathy, dysarthria, impaired judgment, and maladaptive behavior (Danzl and Pozos, 1994~. In contrast to the chronic exposure to cold that causes these changes, even acute exposure to cold environments will cause hallucinations without any other signs of hypothermia (Lloyd, 19831.
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From page 153... ...
what is the effect of ambient temperature on the subject during REM and NREM sleep. It has been commonly reported that changes in body temperature and metabolic rate at sleep onset in humans suggest a "decrease" in the regulation of core temperature.
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From page 154... ...
in constant exposure to a cold environment, it is very probable that he/she will suffer a drop in core temperature leading to secondary hypothermia and death (Pugh, 1966~. It should be emphasized that, before this point is reached, the higher mental dysfunctions that are associated with sleep deprivation and/or cold stress will be evident.
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From page 155... ...
He studied groups living in various parts of the world and noted that when the subjects were sleeping there were diverse physiological responses to the cold environment. His subjects included Australian aborigines, bushmen of the Kalahari Desert, Alacaluf Indians of Tierra del Fuego, Arctic Indians, Andean Indians, Eskimos, and Lapps.
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From page 156... ...
Although helpful, these studies do not shed light on the overall physiological adjustments that occur during field conditions. With the advent of miniaturized recording equipment, it should be possible to record skin temperatures and physical activity from NATO military forces in Bosnia.
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From page 157... ...
for 14 male subjects sleeping in military sleeping bags for 6 hours. Sleeping bags are temperature specific for temperatures: 30°, 5°, and-20°C (86°, 41°, and - °F)
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From page 158... ...
In general, the human body is robust enough to handle these challenging changes by utilizing behavioral and physiological responses. Research results from strictly controlled laboratory settings will assist in the development of possible biological/pharmacological agents that may alter circadian and other biological clocks to enhance human performance in adverse environmental settings.
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From page 159... ...
Moore-Ede 1981 Circadian rhythm of body temperature persist after suprachiasmatic lesions in the squirrel monkey.
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From page 160... ...
Mrolsovsky 1989 Effects of induced wheel running on the circadian activity rhythms of Syrian hamsters: Entrainment and phase response curve.
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