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Sleep. 2018 Oct 1;41(10). doi: 10.1093/sleep/zsy153.

The effect of zolpidem on cognitive function and postural control at high altitude.

Author information

1
Intensive Care Unit, Grenoble Alpes University Hospital, Grenoble, France.
2
Grenoble Institute of Neurosciences, INSERM, Grenoble, France.
3
HP2 Laboratory, Grenoble Alpes University, INSERM, Grenoble, France.
4
Laboratoire de Psychologie Cognitive (LPC), UMR, CNRS, Aix-Marseille Université, Marseille, France.
5
Laboratoire de Neurosciences Cognitives (LNC), UMR, CNRS, Aix Marseille Université, Marseille, France.
6
Laboratorio Antidoping, Federazione Medico Sportiva Italiana, Rome, Italy.
7
Department of Experimental Medicine, Sapienza University of Rome, Italy.
8
National school for mountain sports (ENSM), Chamonix, France.

Abstract

Study Objectives:

Sleep is altered at high altitude leading many mountaineers to use hypnotics in order to improve sleep efficiency. While after a full night at altitude the short-acting hypnotic zolpidem does not appear to alter cognitive function, residual adverse effects should be considered following early waking-up as performed by mountaineers. We hypothesized that zolpidem intake at high altitude would alter cognitive function 4 hours after drug intake.

Methods:

In a randomized double-blind controlled cross-over study, 22 participants were evaluated during two nights at sea level and two nights at 3800 m, 4 hours after zolpidem (10 mg) or placebo intake at 10:00 pm. Polygraphic recording was performed until waking-up at 01:30 am. Sleep quality, sleepiness and symptoms of acute mountain sickness were assessed by questionnaires. Two cognitive tasks (Simon task and duration-production task) were performed at rest and during exercise and postural control was evaluated.

Results:

Zolpidem increased reaction time in all conditions (zolpidem 407 ± 9 ms vs. placebo 380 ± 11 ms; p < 0.001) and error rate in incongruent trials only (10.2 ± 1.1% vs. 7.8 ± 0.8%; p < 0.01) in the Simon task and increased time perception variability (p < 0.001). Zolpidem also altered postural parameters (e.g. center of pressure area, zolpidem 236 ± 171.5 mm2 vs. placebo 119.6 ± 59 mm2; p < 0.001). Zolpidem did not affect apnea-hypopnea index and mean arterial oxygen saturation (p > 0.05) but increased sleep quality (p < 0.001). Zolpidem increased symptoms of acute mountain sickness and sleepiness (p < 0.05).

Conclusions:

Acute zolpidem intake at high altitude alters cognitive functions and postural control during early wakening which may be deleterious for safety and performances of climbers.

PMID:
30099547
DOI:
10.1093/sleep/zsy153

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