[Waking-sleeping transition in the newborn baby and in infants before the age of 3 months (author's transl)].

The mode of transition from waking to sleeping was studied using two methods: (1) by the simple observation of behavioural criteria (opening and closing of eyes, crying, motility), and in particular, rapid eye movements (REM); (2) from combined behavioural and polygraphic criteria (recorded REM, chin EMG, respiratory rhythm, EEG). This study shows that sleep may begin without complete eye closure, with half closed eyes or with brief, alternating opening and closing of the eyes. The modifications of the various polygraphic and behavioural parameters depend on the stage of sleep which is the outcome. The changes which most often condition the passage to a given stage of sleep are the following: (a) inhibition of the tonic chin EMG in the transition towards active sleep (AS); (b) modifications of the EEG in the transition towards quiet sleep (QS); (c) stopping of crying and of agitation in the transition towards indeterminate sleep (IS). The comparison of results obtained using the two methods of analysis shows that the simple observation of behavioural parameters overestimates the number of sleep inductions in AS. This method does not take into account discordances between polygraphic parameters. This study confirms the reduction with age of sleep onsets in AS, with a concomitant increase in sleep onsets in QS. It stresses the variability in the mode of onset of sleep in normal children of the same age group, as well as in successive sleep inductions in the same child.