Jet lag can prompt relapses of psychotic disorders and could trigger new cases in predisposed individuals.
A study of 152 foreign tourists admitted to the Kfar Shaul Mental Health Centre in Jerusalem between 1993 and 1998 found that those who had crossed seven or more time zones were much more likely to suffer episodes than those who had passed through three or fewer.
The disruption of the body clock caused by jet lag is known to lead to fatigue, headaches, irritability and gastrointestinal disorders. The evidence collected by Gregory Katz, director of the acute intervention ward at the Kfar Shaul Hospital, indicates that it could also have a serious impact on mental health.
Dr Katz said the study raises concerns in an age when there are growing numbers of long-distance travellers.
"People who have a previous history of affective or psychiatric states should be cautious about flying without getting some preventive treatment from a consulting psychiatrist," he said.
The research, to be published in the journal Comprehensive Psychiatry , involved 81 patients from North and South America, the East Asia and Australia - who had travelled eastwards across at least seven time zones - and 71 from Europe, whose journeys covered at most three time zones.
Twenty eight per cent of the first group suffered symptoms of a psychotic episode or affective disorder within seven days of landing having had no previous psychiatric history or having been in full remission for at least a year prior to the flight.
Just 13 per cent of the second group were similarly affected.
In 11 cases, a first psychiatric episode seemed to have a link with jet lag, though the number was not statistically significant.