title: The effects of napping on cognitive function in preschoolers.
abstract: OBJECTIVE
  To determine the relationship between napping and cognitive function in preschool-aged children.
  
  
  METHODS
  Daytime napping, nighttime sleep, and cognitive function were assessed in 59 typically developing children aged 3 to 5 years, who were enrolled in full-time childcare. Participants wore an actigraphy watch for 7 days to measure sleep and napping patterns and completed neuropsychological testing emphasizing attention, response control, and vocabulary. Parents of participants completed behavior ratings and sleep logs during the study. Sleep/wake cycles were scored with the Sadeh algorithm.
  
  
  RESULTS
  Children who napped more on weekdays were also more likely to nap during weekends. Weekday napping and nighttime sleep were inversely correlated, such that those who napped more slept less at night, although total weekday sleep remained relatively constant. Weekday napping was significantly (negatively) correlated with vocabulary and auditory attention span, and weekday nighttime sleep was positively correlated with vocabulary. Nighttime sleep was also significantly negatively correlated with performance, such that those who slept less at night made more impulsive errors on a computerized go/no-go test.
  
  
  CONCLUSIONS
  Daytime napping is actually negatively correlated with neurocognitive function in preschoolers. Nighttime sleep seems to be more critical for development of cognitive performance. Cessation of napping may serve as a developmental milestone of brain maturation. Children who nap less do not appear to be sleep deprived, especially if they compensate with increased nighttime sleep. An alternative explanation is that children who sleep less at night are sleep deprived and require a nap. A randomized trial of nap restriction would be the next step in understanding the relationship between napping and neurocognitive performance.
authors.affiliation: Department of Pediatrics, University of Maryland, Baltimore, MD, USA.
authors.forename: Janet C
authors.initials: JC
authors.lastname: Lam
authors.forename: E Mark
authors.initials: EM
authors.lastname: Mahone
authors.forename: Thornton
authors.initials: T
authors.lastname: Mason
authors.forename: Steven M
authors.initials: SM
authors.lastname: Scharf
mesh_terms: D056044:Actigraphy; D000204:Activity Cycles; D002657:Child Development; D002675:Child, Preschool; D003071:Cognition; D005260:Female; D006801:Humans; D008297:Male; D008396:Maryland; D012890:Sleep