THE ROLE OF SLOW-WAVE SLEEP ON THE DURATION OF QUIET SLEEP IN INFANTS

The duration of quiet sleep (QS) phases has been shown to increase dur ing the first year of life. Slow-wave sleep (SWS) appears in about hal f of the QS phases beyond 20 weeks. In order to evaluate the role of S WS in the lengthening of QS phase duration during the first year of li fe, we looked at 48 normal full-term infants (aged between 1 and 54 we eks), recorded for a whole-night period. Records included electro-ence phalogram (EEG) and other polygraphic parameters. Infants were separat ed into two groups: (1) those who did not show SWS episodes at all, an d (2) those who show both QS phases with (QS SWS+) and without (QS SWS -) SWS episodes. In group 2 the duration of QS SWS+ was longer than th at of QS SWS, as well as longer than that of QS of group 1. Group 1 ha d a duration of QS phases similar to that of QS SWS-. The duration of QS SWS+ depended both on the SWS latency and SWS duration. The lengthe ning of QS phases with age is accounted for by those phases containing SWS episodes, reflecting a maturational restructuring of QS.