The Relationship Between The Early Sleep Of Preterm Infants And Executive Function At Preschool Age

Objective:The purpose of this study was to explore the relationship between the early sleep of preterm infants and cognitive flexibility,working memory and inhibition control of three components of executive function at preschool age.Methods:In this study,twenty-seven preterm infants were enrolled.Sleep data was monitored for consecutive days by an actigraphy at six month of gestational age(GA).The monitoring began from the Tuesday night when preterm infants started nocturnal sleep and ended on the Friday morning when preterm infants waked up in the morning.Monitoring events included daytime sleep,the number of daytime sleep,the proportion of daytime sleep,wake-up time,bedtime of nocturnal sleep,latent period of nocturnal sleep,nocturnal sleep duration,the number of nighttime awakening,the longest continuous nocturnal sleep duration,24 h sleep duration,sleep efficiency and morning wake time.Cognitive flexibility,working memory and inhibition control was evaluated by Dimensional Change Card Sort(DCCS),The Digit Span Forwards and Backwards test,and Delay of Gratification at 4-5 years old.The score of the post-switch in DCCS,score of digits forward(DF)and the Digit Span Backwards,and waiting time were recorded.Statistically significant difference in gender in cognitive flexibility,working memory and inhibition control was compared.The relationship between all the sleep parameters and brain executive function was analyzed.Results:(1)There was no significant difference in gender in color-size task and color-shape task(P >0.05,P >0.05).There was positive correlation between wake-up time and score of the post-switch in color-size task(r=0.328,P <0.05).There was positive correlation between wake-up time and score of the post-switch in color-shape task(r=0.326,P<0.05).There was no correlation between other sleep parameters and score of the post-switch(P >0.05).(2)The score of DF was averagely 7.28.The score of The Digit Span Backwards was averagely 0.81.There was no significant difference in gender in DF and The Digit Span Forwards test(P >0.05,P >0.05).No correlation between all of sleep parameters and score of DF were found in The Digit Span Forwards test(P >0.05).There was positive correlation between daytime sleep duration and score of The Digit Span Backwards(r=0.320,P<0.05).There was no correlation between other sleep parameters and score of The Digit Span Backwards(P >0.05).(3)Waiting time of 27 preterm infants was averagely 2.30 min.There was no significant difference in gender in color-size task Delay of Gratification(P >0.05,P >0.05).There was negative correlation between bedtime of nocturnal sleep and waiting time(r=-0.330,P<0.01).There was no correlation between other sleep parameters and waiting time(P >0.05).Conclusions:The relationship between wake-up time,daytime sleep and bedtime of nocturnal sleep and the development of cognitive flexibility,working memory and inhibition control at preschool age was found.This study proposed to pay attention to the impact of sleep on development,early sleep intervention and daily schedule to improve the later neurodevelopment of preterm infants.