[Functions of paradoxical sleep and ontogenesis]

The hypotheses directly linked to cognitive and neurologic ontogenic processes ie consolidation of memory and learning, the maturation hypothesis of Roffwarg and the hypothesis of endogenous genetic programming of Jouvet, are analysed. The discussion of these theories are based on the analysis of: the neurophysiologic mechanism of REM sleep and its ontogenesis in human, the results of REM sleep deprivation in young animals and by a personal study of facial mimics during sleep in neonates. Active sleep could be assimilated, very early during ontogenesis, to REM sleep, it probably plays an important role in brain maturation during early development but the stimulation is probably, at this time, not very specific, later it could be a link between genetic programming and epigenetic processes.