Influence of Zolpidem and Sleep Inertia on Balance and Cognition During Nighttime Awakening: A Randomized Placebo-Controlled Trial

Authors

  • Danielle J. Frey PT, PhD,

    1. From the *Sleep and Chronobiology Laboratory and Locomotion Laboratory, Department of Integrative Physiology, Center for Neuroscience, University of Colorado at Boulder.
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  • Justus D. Ortega PhD,

    1. From the *Sleep and Chronobiology Laboratory and Locomotion Laboratory, Department of Integrative Physiology, Center for Neuroscience, University of Colorado at Boulder.
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  • Courtney Wiseman BA,

    1. From the *Sleep and Chronobiology Laboratory and Locomotion Laboratory, Department of Integrative Physiology, Center for Neuroscience, University of Colorado at Boulder.
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  • Claire T. Farley PhD,

    1. From the *Sleep and Chronobiology Laboratory and Locomotion Laboratory, Department of Integrative Physiology, Center for Neuroscience, University of Colorado at Boulder.
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  • Kenneth P. Wright Jr., PhD

    1. From the *Sleep and Chronobiology Laboratory and Locomotion Laboratory, Department of Integrative Physiology, Center for Neuroscience, University of Colorado at Boulder.
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Address correspondence to Kenneth P. Wright Jr., Department of Integrative Physiology, 1725 Pleasant Street; Clare Small 114, University of Colorado at Boulder, Boulder, CO 80309-0354. E-mail: kenneth.wright@colorado.edu

Abstract

OBJECTIVES: To determine whether sleep inertia (grogginess upon awakening from sleep) with or without zolpidem impairs walking stability and cognition during awakenings from sleep.

DESIGN: Three within-subject conditions hypnotic medication (zolpidem), placebo (sleep inertia), and wakefulness control randomized using balanced Latin square design.

SETTING: Sleep laboratory.

PARTICIPANTS: Twelve older and 13 younger healthy adults.

INTERVENTION: 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).

MEASUREMENTS: 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.

CONCLUSION: 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.

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