[Impact of sleep duration on cognitive functions among preschoolers].

Objective: To explore the effect of sleep duration including napping, night sleep and total sleep duration on cognitive functions among preschoolers.

Methods: The samples consisted of 94 preschoolers, aged from 2.58 to 6.75 years, from Hangzhou and Beijing. Peabody Picture Vocabulary Test-Revised (PPVT-R), Picture Deletion Task for Preschoolers (PDTP) and Spatial Working Memory Test were applied to assess the cognitive functions of these preschoolers. Basic demographic information and sleep information were collected with self-made questionnaires.

Results: The results of the present study indicated that among all the participants, there were significant grade differences in napping duration and total sleep duration (F0.05(3, 90)=6.346, P=0.001; F0.05(3, 90)=2.925, P=0.038). The total sleep duration was decreased with age. However, the night sleep duration was not changed significantly with age. The correlations between the night sleep and total sleep duration and the scores of attention and working memory were significantly positive (r=0.202-0.282). No significant correlations were noted between the napping and all the scores of cognitive tests. The regression analysis showed that the total sleep duration especially the night sleep duration could well explain the variance of attention and working memory.

Conclusion: Total sleep duration, especially night sleep duration may have great impact on preschoolers' cognitive functions, such as attention and working memory. Enough sound night sleep may help to promote the cognitive functions of the target population.