Seasonal variations in the child and adolescent psychoses.

We examined seasonality effects in a controlled study of children and adolescents with psychotic states. There was a peak of psychotic births between February and March but this pattern did not differentiate psychotics from psychiatrically disturbed controls. Onset of illness was found to be significantly more common in the summer months (June to August) in psychotics than in controls. We discuss possible explanations for this phenomenon.