Circannual fluctuation of a stereotyped behaviour with possible self-mutilation in a mentally deficient adolescent.

A stereotyped behaviour with possible self-mutilation was measured in a mentally deficient child (age 17) with autistic features; the subject was observed 5 minutes each hour, daily from 0800 to 2000, for fourteen months. We studied variations of his behaviour (number of acts per minute of observation and per day) and especially circannual fluctuations with maximum in summer and minimum in winter. The origins of this variation are discussed, particularly from the chronobiological point of view. Eventual therapeutic issues of this kind of study are also considered.