title: Influence of zolpidem and sleep inertia on balance and cognition during nighttime awakening: a randomized placebo-controlled trial.
abstract: OBJECTIVE
  To determine whether sleep inertia (grogginess upon awakening from sleep) with or without zolpidem impairs walking stability and cognition during awakenings from sleep.
  
  
  METHODS
  Three within-subject conditions hypnotic medication (zolpidem), placebo (sleep inertia), and wakefulness control randomized using balanced Latin square design.
  
  
  METHODS
  Sleep laboratory.
  
  
  METHODS
  Twelve older and 13 younger healthy adults.
  
  
  METHODS
  Five milligrams of zolpidem or placebo 10 minutes before scheduled sleep (double-blind: zolpidem or sleep inertia); placebo before sitting in bed awake for 2 hours after their habitual bedtime (single-blind: wakefulness control).
  
  
  METHODS
  Tandem walk on a beam and cognition, measured using computerized performance tasks, approximately 120 minutes after treatment.
  
  
  RESULTS
  No participants stepped off the beam on 10 practice trials. Seven of 12 older adults stepped off the beam after taking zolpidem, compared with none after sleep inertia and three after wakefulness control. Fewer young adults stepped off the beam: three after taking zolpidem, one after sleep inertia, and none after wakefulness control. Number needed to harm analyses showed one tandem walk failure for every 1.7 (95% confidence interval (CI)=1.4-2.0) older and 5.5 (95% CI=5.2-5.8) younger adults treated with zolpidem. Cognition was significantly more impaired after zolpidem exposure than with wakefulness control in older and younger participants (working memory: older, -4.3 calculations, 95% CI=-7.0 to -1.7; younger, -12.4 calculations, 95% CI=-18.2 to -6.7; Stroop: older, 76-ms increase (95% CI=13.5-138.4 ms); younger, 126-ms increase, 95% CI=34.7-217.5 ms), whereas sleep inertia significantly impaired cognition in younger but not older participants.
  
  
  CONCLUSIONS
  Zolpidem produced clinically significant balance and cognitive impairments upon awakening from sleep. Because impaired tandem walk predicts falls and hip fractures and because impaired cognition has important safety implications, use of nonbenzodiazepine hypnotic medications may have greater consequences for health and safety than previously recognized.
authors.affiliation: Sleep and Chronobiology Laboratory, Department of Integrative Physiology, Center for Neuroscience, University of Colorado at Boulder, Boulder, CO, USA.
authors.forename: Danielle J
authors.initials: DJ
authors.lastname: Frey
authors.forename: Justus D
authors.initials: JD
authors.lastname: Ortega
authors.forename: Courtney
authors.initials: C
authors.lastname: Wiseman
authors.forename: Claire T
authors.initials: CT
authors.lastname: Farley
authors.forename: Kenneth P
authors.initials: KP
authors.lastname: Wright
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control*; D000328:Adult; D000367:Age Factors; D000368:Aged; D000704:Analysis of Variance; D003071:Cognition / Q000187:drug effects*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D008297:Male; D004856:Postural Balance / Q000187:drug effects*; D011725:Pyridines / Q000494:pharmacology*; D012449:Safety; D012890:Sleep / Q000502:physiology*; D000077334:Zolpidem
chemical_list: D006993:Hypnotics and Sedatives; D011725:Pyridines; D000077334:Zolpidem