title: The prospective impact of sleep duration on depression and mania.
abstract: OBJECTIVE
  Many patients report sleeping less than 6 h per night during episodes of depression and mania. This type of sleep deficit may also be a risk factor for subsequent mood episodes; however, the long-term impact of sleep deficit remains unclear. The current study is among few longitudinal studies to assess the prospective effect of sleep deficit on depression and mania.
  
  
  METHODS
  A subsample of 54 individuals from a longitudinal study of bipolar I disorder was selected. Participants entered the study during a mood episode. Baseline symptom data were collected at month 4 to allow for recovery from the initial episode, sleep was assessed at month 6, and follow-up symptom data were obtained during months 7-12.
  
  
  RESULTS
  Sleep deficit predicted depressive symptoms across the 6-month follow-up but not mania.
  
  
  CONCLUSIONS
  It is likely that the impact of sleep deficit on mania was probably missed because assessments covered a full month. Monitoring sleep duration may help predict depression in bipolar disorder and provide an opportunity for targeting intervention.
authors.affiliation: Department of Psychiatry, Massachusetts General Hospital, Boston, MA 02114, USA. cperlman@partners.org
authors.forename: Carol A
authors.initials: CA
authors.lastname: Perlman
authors.forename: Sheri L
authors.initials: SL
authors.lastname: Johnson
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Mellman
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology*; D003866:Depressive Disorder / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D015995:Prevalence; D012720:Severity of Illness Index; D012892:Sleep Deprivation / Q000453:epidemiology*