[One chronobiological aspect of sterotyped behaviour (author's transl)]

The stereotyped behaviours of six institutionalized handicapped children were continuously observed during several days. Each child showed at least two forms of stereotyped behaviour. Using spectra of variance and cross-correlation analysis, the data were analysed with respect to underlying periodicities. A 2.5-hour cycle was found in all observed stereotypies. Furthermore, stable phase relationships were found between the periodic variations of different stereotypies in one and the same child. The temporal courses of hand and oral stereotypies were synchronous but head and whole-body stereotypies were delayed by half a phase with respect to sterotypic handwaving. A possible relationship is discussed between the 2.5-hour periodicity of stereotyped behaviour and Kleitman's "Basic Rest Activity Cycle."