Air Travel and Jet-Lag

Abstract

Air travel crossing time-zones is associated with shifts in local time. The changes occur very rapidly and cause mismatching between external time cues and the internal body clock. The biological systemis unable to adjust immediately to the new local time, and it can take several days or even weeks before complete synchrony is regained. During the transition from the preflight to the postflight steady state, not only physiological functions are affected, but alsothe rhythms of performance and behavior. Magnitude and duration of these changes are influenced by number of time zones, individual propensity and flight direction. In general, the effects are more pronounced and resynchronization occurs more slowly after eastward flights than after westward ones. Jet-lag is now being used as the term for a variety of symptoms that are experienced: reduced well- being, impaired body functions, sleep disturbances, as well as dizziness and fatigue at unusual times of the local day. Several approaches have been investigated to alleviate the negative jet-lag effects. Hypnotics and hormonal substances, bright light and special diets are among the countermeasures presently under consideration. Recent studies indicate that intensity and duration of the jet-lag syndrome can also be reduced by pre-adjustment and appropriate changes in the wake-sleep cycle. However, there is no ideal treatment that will have beneficial effects under all circumstances and for all air travelers.