ABSTRACT
Two hundred and eighty cases examined by court order by the district psychiatry office in the southern district of Israel in the past three years (1988-90) were critically reviewed. Analysis of the monthly distribution of criminal acts throughout the year shows a specific pattern of monthly occurrence of aggressive criminal acts (annual rhythm). This rhythm shows peaks in February and the summer months (June, July, August) and nadirs in March, October, November and December. The monthly occurrence of non-aggressive criminal acts showed a different pattern as compared with the annual rhythm of aggressive criminal acts. A correlation was found between the annual rhythm of aggressive criminal acts and the annual photoperiod (day length) rhythm. There was a significant positive correlation between these rhythms. We also analysed the age dependent distribution of aggressive criminal acts. A continuous age dependent increase in the percentage rate of aggressiveness was found.