Electrophysiological semiology of day sleep in children

Abstract The afternoon sleep of 12 children aged 7–9 was studied; its electrophysiological indices and sequential organization were described and compared to those of afternoon sleep of adults and to those of night sleep of adults and children. The EEG indices which differentiate sleep patterns of children from adults' were the following: abundance of slow rhythms from onset of sleep; absence of low voltage fast activity at sleep onset and during REM sleep; early appearance of a large amount of transitory potentials in the form of sharp rolandic waves and sharp occipital waves. Moreover, either focal or generalized paroxysmal discharges occasionally occurred. Even when it covers a complete sleep cycle, the afternoon sleep of children appears shorter than both that of adults and the first cycle of night sleep in children of the same age. The organization of sleep components does not allow identification of the classical stages defined in adults nor to describe homogeneous stages which are specific to children. The very atypical character of REM sleep also makes it difficult to differentiate unequivocally the classical slow and paradoxical sleeps. The significance of rolandic and occipital sharp transients is discussed; the role of maturation and the influence of the time of occurrence within the circadian rhythm are considered, in order to explain the phenomenological and temporal characteristics of day sleep in children.