title: Sleep duration and all-cause mortality: a critical review of measurement and associations.
abstract: OBJECTIVE
  Variation in sleep duration has been linked with mortality risk. The purpose of this review is to provide an updated evaluation of the literature on sleep duration and mortality, including a critical examination of sleep duration measurement and an examination of correlates of self-reported sleep duration.
  
  
  METHODS
  We conducted a systematic search of studies reporting associations between sleep duration and all-cause mortality and extracted the sleep duration measure and the measure(s) of association.
  
  
  RESULTS
  We identified 42 prospective studies of sleep duration and mortality drawing on 35 distinct study populations worldwide. Unlike previous reviews, we find that the published literature does not support a consistent finding of an association between self-reported sleep duration and mortality. Most studies have employed survey measures of sleep duration, which are not highly correlated with estimates based on physiologic measures.
  
  
  CONCLUSIONS
  Despite a large body of literature, it is premature to conclude, as previous reviews have, that a robust, U-shaped association between sleep duration and mortality risk exists across populations. Careful attention must be paid to measurement, response bias, confounding, and reverse causation in the interpretation of associations between sleep duration and mortality.
authors.affiliation: Department of Health Studies, University of Chicago, IL, USA. lkurina@health.bsd.uchicago.edu
authors.forename: Lianne M
authors.initials: LM
authors.lastname: Kurina
authors.forename: Martha K
authors.initials: MK
authors.lastname: McClintock
authors.forename: Jen-Hao
authors.initials: JH
authors.lastname: Chen
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Waite
authors.forename: Ronald A
authors.initials: RA
authors.lastname: Thisted
authors.forename: Diane S
authors.initials: DS
authors.lastname: Lauderdale
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002423:Cause of Death; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment / Q000379:methods; D012890:Sleep / Q000502:physiology*; D013997:Time Factors