Violence in hospitalized psychiatric patients: diurnal and seasonal patterns.

The use of four-point physical restraints on a single occasion or repeatedly in psychiatric inpatients was followed prospectively during 1993 in Beer Sheva Mental Health Center. Mood-disordered patients had significantly more restraints per patient than did schizophrenic and schizoaffective patients. The monthly rates of restraints of mood-disordered and schizophrenic patients were found to be negatively correlated with the duration of the daily photoperiod, which was phase-advanced by a month. The findings suggest that seasonality (the duration of the daily photoperiod) should be taken into account in attempts to predict the potential dangerousness of psychiatric patients.