| Abstract: | The aim of this work is to study the human' SWC development in the first six years of life, in a longitudinal approach. Six boys, attending the same kindergarten at University of São Paulo, participated in the study. Data were collected on five different occasions, from the second to the sixth year of life. On each occasion, the sleep/wake behavior was followed for seven consecutive days (Sunday to Saturday) by an observer at the kindergarten and at home by the parents. Mean total sleep duration as well mean diurnal sleep duration (episodes from 7 AM to 7 PM) and night sleep duration (7 PM to 7 AM) were obtained for all subjects. Data were compared by ANOVA for repeated measures and processed using the Fast Fourier Transform to obtain the power spectrum of the sleep/wake oscillations. Results were submitted to a test of compound periodicities, to detect the significant components of the spectrum. This test generates, for each frequency, a value (Y), which represents the contribution of this frequency to overall rhythmicity. Results showed an age effect on total sleep duration (p<0.05), due to a reduction of diurnal sleep (p<0.01). An age effect on night sleep duration was not observed. Differences were observed in the age of disappearance of diurnal sleep behavior. An increase in the sleep/wake circadian component was observed for all children. Individual differences in this component were found coinciding with the disappearance of diurnal sleep episodes. As the children lived the same temporal patterns at the kindergarten the interindividual differences which were found can be explained by different temporal patterns at home and/or by individual differences in maturation of the circadian timing system. |
