The timing of acts of deliberate self-harm: is there any relation with suicidal intent, mental disorder or psychiatric management?

OBJECTIVE: To investigate the common perception that more serious suicide attempts tend to occur earlier in the day.
METHODS: Prospective study of 158 adults referred for psychiatric assessment from the general hospital following an episode of deliberate self-harm. The main outcome measures used were Beck's Suicide Intent score, ICD-10 psychiatric diagnosis, alcohol consumption at the time of the attempt, and follow-up decision recorded by the interviewing duty psychiatrist. The patient also completed a checklist of current precipitating problems.
RESULTS: A marked circadian variation in timing of the act was found, peaking between 2200 and 2400 h. "Early" acts (0300-1459 h) were significantly less likely to involve alcohol consumption, more likely to lead to admission to a medical ward, and involved more patient-identified problems than "late" acts. People who took overdoses early in the day were more likely to have concerns about their own mental health. Compared to earlier acts of self-harm, late evening (2200-2359 h) cases were less likely to be diagnosed as depressed or offered psychiatric follow up. No relation was found between time of day of self-harm and Beck's Suicide Intent score.
CONCLUSIONS: Implications arise regarding clinical risk assessment and current staffing levels in the accident and emergency department. The interviewing psychiatrist could concentrate on excluding depression and teaching problem solving to those who self-harm in the morning or afternoon, and on the detection and treatment of alcohol dependence for late evening cases.