Circadian rhythm of parasuicide in relation to violence of method and concomitant mental disorder.

Circadian occurrence of parasuicide was evaluated in relation to sex, violence of parasuicide method and psychiatric diagnosis. In all, 457 consecutive episodes of parasuicide were recruited during a 5-year period. Complete data for time of parasuicide, parasuicide method, parasuicide recurrency and psychiatric diagnosis (ICD-9) were available for 304 subjects. Parasuicide methods were classified into two groups depending on the violence of the method. Parasuicide occurred significantly more often in the afternoon and evening hours for both men and women, for both violent and non-violent methods, both in first-even cases and repeaters, and in the following diagnostic groups: organic mental and psychoactive substance disorders, neurotic disorders and personality disorders. The data support the hypothesis of a circadian rhythmicity of parasuicide, showing an area of chronobiological risk in the afternoon and early evening hours.