Time Zone Change and Major Psychiatric Morbidity: The Results of a 6-Year Study in Jerusalem G. Katz, H.Y. Knobler, Z. Laibel, Z. Strauss, and R. Durst Psychiatric morbidity among foreign tourists is usu- ally connected to external factors such as unfamiliar surroundings, language problems, and specialreli- gious experiences, as wellas biological factors such as dyschronism ofcircadian rhythms. Long-range flights through several time zones are typically fol- lowed by symptoms of jet lag such as fatigue, severe sleep schedule disturbance, impairment of cognitive functions, and even mild depression. Jet lag is gener- ally attributed to a conflict between external time cues and internal biological rhythms. This study ex- amined 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 ⴝ 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 ⴝ 81); and group II, three time zones or less (n ⴝ 71). The direction of flight was mainly eastbound. After controlling the two groups for demographic and religious background, past psy- chiatric 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) ab- sence 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 ⴝ .5), whereas the number of relapses conjoint with jet lag in the seven or more time zone group was significantly higher ( P ⴝ .04). The results suggest that the dyschronism of circadian rhythms and jet lag possibly play a role in the exac- erbation of major psychiatric disorders. Copyright © 2002 by W.B. Saunders Company R APID DYSCHRONISM of internal circadian rhythms following long distance flights may cause a variety of unpleasant symptoms such as fatigue, headache, irritability, lossof concentra- tion,and gastrointestinal disorders. 1 These symp- toms,known as jet lag,lastfor several days and usually no serious complications are observed. Generally, jet lag is more severe among older trav- elers and after eastward flights with multiple time zone changes. 2 A connection between psychiatric morbidity and time zone change has been sug- gested in the literature, 3 although, in general, the chronobiological aspects of psychiatric morbidity among travelers have been underinvestigated. In thisstudy,an attempt is made to evaluate the possible psychiatric aspects of jet lag. One of the main problems in conducting con- trolled and large-scale studies in this area is the lack of psychiatric institutions specializing in the treatment of travelers. The Kfar ShaulMental Health Center is a unique facility in this respect in that almost all visitors to Jerusalem who succumb to psychotic breakdown are automatically referred there for evaluation. 4-6 Research into this phenom- enon has also been hampered by standardization problems but these are largely overcome by the recently introduced syndrome-specific scalefor measuring severity of jet lag. 7 The aim of the present study was to examine the relation of jet lag with the appearance of psychi- atric symptoms among tourists hospitalized in Kfar Shaul Hospital during the years 1993 to 1998. METHOD Demographic and psychiatric data were collected on all for- eign tourists (n ⫽ 152) admitted to the Kfar ShaulMental Health Center over a 6-year period (1993 to 1998). The demo- graphic data included gender, age, marital status, education, and religious background; the psychiatric data included diagnosis after referral (according DSM-IV) and information regarding past psychiatric history and recent psychiatric condition 1 year prior to the journey and the flight to Israel. Travel history has been obtained from various sources: the patient, his/her family, treating doctors, accompanying persons, etc.Patientconsent was obtained prior to inclusion in this prospective, open clinical trial. For geopolitical reasons, foreign visitors to Israel usually arrive by air and experience a time zone change of 7 hours or more (from North and South America, the Far East and Aus- tralia), or 3 hours or less (from European countries). This allows for two groups (referred to as group I and group II, respectively) to be distinguished and compared for the possible influence of jet lag on either the first appearance of a psychotic or affective From the Kfar Shaul Mental Health Center, affiliated with the Hebrew University, Hadassah Medical School, Jerusalem, Is- rael. Address reprint requests to Gregory Katz, M.D.,Kfar Shaul Hospital, Givat Shaul, Jerusalem, 91060. Copyright © 2002 by W.B. Saunders Company 0010-440X/02/4301-0008$35.00/0 doi:10.1053/comp.2002.29849 Comprehensive Psychiatry, Vol. 43, No. 1 ( January/February), 2002: pp 37-40 37