title: Estrogen replacement therapy moderates the sleep disruption associated with nocturnal blood sampling.
abstract: OBJECTIVE
  To determine whether chronic oral estrogen replacement therapy (ERT) (1) improves the sleep of older, non-symptomatic postmenopausal women; and (2) reduces the sleep disruption associated with a stressor (frequent remote nocturnal blood-sampling through an intravenous catheter).
  
  
  METHODS
  Descriptive, cross-sectional, secondary analysis of a larger study.
  
  
  METHODS
  The General Clinical Research Center at the University of Washington Medical Center.
  
  
  METHODS
  Women aged 57-80 (mean age = 70) at least 5 years past menopause were recruited from the community. Hot flashes and significant sleep difficulties were exclusion criteria. The ERT group (n=37) consisted of women on chronic oral ERT for > or = 2 years. The NERT group (n=56) consisted of women not using estrogen (NERT) for > or = 2 years.
  
  
  METHODS
  N/A.
  
  
  RESULTS
  Following an adaptation night, polysomnographic measures were collected for 2 consecutive nights. A blood sample was collected every 20 minutes for the last 24 hours (including Night 2), through an intravenous catheter. The only group difference in sleep on the baseline (non-catheter) night was that NERT women had a shorter sleep latency. Sleep on the catheter night was characterized by increased wakefulness, longer sleep latency, and decreased REM sleep for both groups relative to the baseline. However, the impact of nocturnal blood sampling was much greater for NERT than for ERT women: they experienced significantly greater percent changes in more sleep-wake variables, particularly slow-wave sleep (SWS).
  
  
  CONCLUSIONS
  In this cross-sectional study, the use of chronic oral ERT was associated with little effect on the sleep of older postmenopausal women not experiencing hot flashes, except in the presence of a challenge to sleep. ERT ameliorated the disruptive effect of nocturnal blood sampling on both objectively assessed and subjectively assessed sleep.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle 98195, USA. kemoe@u.washington.edu
authors.forename: K E
authors.initials: KE
authors.lastname: Moe
authors.forename: L H
authors.initials: LH
authors.lastname: Larsen
authors.forename: M V
authors.initials: MV
authors.lastname: Vitiello
authors.forename: P N
authors.initials: PN
authors.lastname: Prinz
mesh_terms: D000368:Aged; D001800:Blood Specimen Collection / Q000523:psychology*; D002940:Circadian Rhythm; D003430:Cross-Sectional Studies; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D008875:Middle Aged; D012892:Sleep Deprivation / Q000209:etiology* / Q000628:therapy*; D012895:Sleep, REM / Q000502:physiology; D014851:Wakefulness / Q000502:physiology