title: Minimal Effect of Daytime Napping Behavior on Nocturnal Sleep in Pregnant Women.
abstract: OBJECTIVE
  To assess whether daytime naps negatively impact nocturnal sleep.
  
  
  METHODS
  Longitudinal, prospective cohort design.
  
  
  METHODS
  161 pregnant women recruited and evaluated in early gestation (10-20 weeks).
  
  
  RESULTS
  Daily sleep information was collected in three 2-week periods (10-12, 14-16, and 18-20 weeks gestation) with a daily sleep diary and an actigraph. The average number of naps, as well as the average length of each nap, were calculated from sleep diaries. Women were categorized first as non nappers (0 naps/2-week period), moderate nappers (1-3 naps/2-week period), or frequent nappers (≥ 4 naps/2-week period). Then, based on the average nap length, they were categorized as short (< 90 min) or long (≥ 90 min) nappers. Nocturnal sleep parameters included SOL, WASO, SE, and TST. SAS procedure MIXED was used for modeling the main effects of nap group and time, and time by nap group interactions. Women who took naps had a decrease in diary-assessed nocturnal TST, but not actigraphy-assessed TST. This observation was group- and time-specific. There were no other group differences. Women who napped ≥ 90 min had poorer diary-assessed SE and lower diary-assessed TST than those who took shorter naps. Length of nap was not associated with any other sleep measures.
  
  
  CONCLUSIONS
  The number of daytime naps have minimal impact on nocturnal sleep parameters; however, long nappers did exhibit modestly impaired sleep continuity and sleep quality. Overall, we propose that daytime naps provide a beneficial countermeasure to the sleep disruption commonly reported by pregnant women. This may be clinically beneficial given that sleep continuity and quality are important correlates of pregnancy outcomes.
  
  
  CONCLUSIONS
  A commentary on this article appears in this issue on page 593.
authors.affiliation: University of Pittsburgh, Pittsburgh, PA.
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Ebert
authors.affiliation: University of Pittsburgh, Pittsburgh, PA.
authors.forename: Annette
authors.initials: A
authors.lastname: Wood
authors.affiliation: University of Pittsburgh, Pittsburgh, PA.|University of Colorado, Colorado Springs, CO.
authors.forename: Michele L
authors.initials: ML
authors.lastname: Okun
mesh_terms: D056044:Actigraphy; D000293:Adolescent; D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008875:Middle Aged; D017286:Polysomnography; D011247:Pregnancy; D011446:Prospective Studies; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology*; D055815:Young Adult
keywords: frequency; naps; pregnancy; sleep; women