[Normal children sleep E.E.Gs from 5 months to 3 years old (author's transl)].

The sleep E.E.G. of the child under 3 years old is characteristic from several points of view: Drowsiness: The hypersynchrony is always observed. It is more continuous in younger children, than in the older one, where only bursts of hypersynchrony are seen. The fast rhythms of low amplitude may exist, during stage 2 sleep, but they are rare. Calm Sleep (C.S.): The vertex humps are more and more acute and sharper from 18 months. The sleep spindles are of high amplitude and frequent at 6 and 8 months. They diminish later. It may be for that reason that III and IV sleep stages seem to be more important after 12 months than before. From 21 months, we have observed an unusual pattern during C.S.: rhythmic and diffuse thêta rhythms of about 6 c/s. Paradoxal sleep (P.S.): If it is possible to observe P.S. during day-naps 8 or 9 months, it is rare later and for recording P.S., it is necessary to record E.E.G.s at night. The E.E.Gs are either a little like stage I E.E.G, or consistent of high and monomorphic delta waves. If it is possible to observe at least 3 complete sleep cycles, the proportion of P.S. is about 20 p. 100 of the total length of the sleep. At least, it is very important, even in medical practice, to record not only E.E.G. but also polygraphic leads: breathing, electro-myogram, electrocardiogram, and to notice also the rapid eyes movements.