Time of psychiatric patient assaults: twenty-year analysis of the Assaulted Staff Action Program (ASAP).

Apparent random acts of violence viewed in the aggregate appear to occur in fairly exacting temporal patterns. This is true of rape, street assaults, and domestic violence, among other acts of violence. Patient assaults on staff as acts of violence should also follow a temporal pattern. This twenty-year retrospective study of assaultive psychiatric patients in one public sector examined the temporal pattern of such assaults. Inpatient assaults were more likely to occur in the summer in the middle ten days of the month, during the first shift at mealtimes. In community settings, assaults were more likely in winter during the first ten days of the month, and on the first shift at noon time. The possible reasons for these time patterns, their possible biological roots, and their implications for emergency services personnel and health care providers were discussed.