Desynchronosis in Commercial Aviation.
The technological breakthroughs of the 20th century have raised many questions regarding physiologic adaptation and environmental adversity. One such area of research involves high speed travel and its effect on biological rhythms. Multiple time zone transitions result in a phenomenon known as desynchronization, or "jet lag." This condition can have significant biological and behavioral consequences; it could even, possibly, represent a potential threat to aircrews involved in transmeridian flights.
The first pilot to experience jet lag was Wily Post. In 1933, he described various physiological alterations incurred while crossing time zones during global flight (Endo et al., 1978, p. 251). These changes resulted primarily from shifts in the body's normal circadian rhythms with respect to signals from the external environment (Winget et al., 1984, p. 1085).
Biological rhythms have been observed in practically all known species of animal. When these physiological fluctuations repeat themselves over a period of approximately 24 hours they are called circadian rhythms. Circadian oscillations can result either from environmental influences or self sustained internal fluctuations. Considerable evidence suggests, however, that in the higher organisms the rhythms are mainly generated internally. For example, in mammals, body temperature rises and falls according to a regular daily schedule. These variations result from internal modulation by organisms' own nervous and endocrine systems (Winget et al., 1984, p. 1086).
Although circadian oscillations are self sustaining, they do not exist in complete independence from the environment. Rather they are coupled and entrained by various external influences, or synchronizers. One primary synchronizer, the photoperiod, is defined as the "ratio of light hours to darkness." This oscillating environmental cue is thought...