to govern circadian timing through some sort of intensity dependent physiological mechanism (Czeisler et al., 1986, p. 667).
In general, high speed travel over a distance of more than 4 time zones causes a shift in the body's circadian rhythms resulting in desynchronosis (Endo et al., 1978, p. 249). Basically, the physiological oscillations' timing falls out of phase; they thus lose their coupling to environmental cues. Various symptoms may include general malaise, sleepiness, irritability, disorientation, confusion, cognitive impairment, decreased psychomotor performance, and distorted perceptions of time and distance (Suvanto et al., 1990, p. 543). In addition, digestive system problems such as constipation may occur as well. The effects of desynchronosis often vary considerably from one individual to the next. For example, studies investigating sleep behavior in these subjects found that the number of times people awaken during the night can range from less than 10 to more than 50 (Dement et al., 1986, p. B26). One major factor associated with the variation in jet lag symptoms is age. Older people tend to adapt to new time zones at a significantly slower rate than younger persons. In addition, lifestyle and personality may also affect a person's response to multiple time zone flights (Graeber et al.: 1986, p. B13). For example, such habits as smoking and the use of alcohol might have a negative influence; whereas physical activities or, perhaps, regular meal times might affect the traveler positively. Even such personality traits as neuroticism, extroversion, and introversion have been said to affect desychronosis. Finally, circadian rhythm chronotype must also be taken into account. "Morning type" people may display different sleep behaviors and experience differences in desynchronosis intensity or duration than, for example, "evening type" people (Suvanto & Ilmarinen, 1987b, p. 644). Recent research has found th...