[Bio-rhythmic as time-structure of postnatal development: observation in behaviour and polygraphic studies in a normal newborn (author's transl)].

The spontaneous sleep-waking behaviour of a male infant, normal with respect to pregnancy, delivery and Apgar score, was observed continuously from birth till the first four months of life. Additionally sleep stages were scored by means of polygraphic method during several weeks. The infant was allowed to sleep and awake according to his own schedule and was fed if his behaviour could be judged as a feeding demand. Using statistical analysis it could be deomonstrated, that the spontaneous sleep-waking behaviour was mainly driven by three endogenous rhythms: The Basic rest aktivity cycle with periods of about 50 minutes, a circafour-hour rhythm already established at term and a circadian periodicity which developed during the first three months of life. So far our results support earlier studies of Kleitman and Engelmann, Parmelee, Hellbrügge etc. The present study, however, gives further evidence, that these rhythms do not run independently, but constitute a system of interacting oscillators. During postnatal development these connected rhythms cause characteristic periodicities of the spontaneous sleep-waking pattern. Since the newborn experiences his world within a basic framework of sleep and waking epochs, the system of interacting, endogenous rhythms may be considered as a structure timing the information process in the developing brain.