Time zone change and major psychiatric morbidity: the results of a 6-year study in Jerusalem

Psychiatric morbidity among foreign tourists is usually connected to external factors such as unfamiliar surroundings, language problems, and special religious experiences, as well as biological factors such as dyschronism of circadian rhythms. Long-range flights through several time zones are typically followed by symptoms of jet lag such as fatigue, severe sleep schedule disturbance, impairment of cognitive functions, and even mild depression. Jet lag is generally attributed to a conflict between external time cues and internal biological rhythms. This study examined the possible association between jet lag and psychiatric morbidity among long-distance travelers hospitalized in the Jerusalem Mental Health Center, Kfar Shaul Hospital between 1993 and 1998. This was a prospective open-label study. Patients (n = 152) were divided into two groups based on the number of time zones crossed in the flight to Israel: group I, seven time zones or more (n = 81); and group II, three time zones or less (n = 71). The direction of flight was mainly eastbound. After controlling the two groups for demographic and religious background, past psychiatric history, and diagnosis on admission (P > 0.1, Fisher's exact test), the possible association between jet lag and psychotic or major affective disorder was evaluated according to the following criteria: (1) absence of major mental problems before the flight or good remission of an existing disorder 1 year or more before flight; and (2) the appearance of psychotic or major affective syndromes during the first 7 days after landing. The number of first psychotic/major affective episodes in both groups presumed as associated with jet lag was found similar (P =.5), whereas the number of relapses conjoint with jet lag in the seven or more time zone group was significantly higher (P =.04). The results suggest that the dyschronism of circadian rhythms and jet lag possibly play a role in the exacerbation of major psychiatric disorders.