Am. J. Respir. Crit. Care Med., Vol 153, No. 6, Jun 1996, 1864-1869.
Effect of zolpidem on sleep and ventilatory patterns at simulated altitude of 4,000 meters
M Beaumont, F Goldenberg, D Lejeune, H Marotte, A Harf and F Lofaso
Laboratoire de Medecine Aerospatiale, Centre d'Essais en Vol, Bretigny- sur-Orge, France.
The purpose of this study was to assess the effect of zolpidem 1 0 mg, a
new imidazopyridine hypnotic drug, on sleep and respiratory patterns at a
simulated altitude of 4,000 meters. Eight male subjects spent three nights
in a decompression chamber. The first study night was spent at the ambient
pressure corresponding to sea level. The two other nights were spent at a
simulated altitude of 4,000 meters with either zolpidem or a placebo in
random order according to a double-blind, crossover design. All subjects
showed periodic breathing (PB) during sleep at simulated high altitude.
Furthermore, altitude was associated with decreases in total sleep time
(TST), slow-wave sleep (SWS), and REM sleep, and with significant increases
in Stage 1 duration and in the arousal index. Most arousals were
synchronous with the hyperpneic phase of PB. The main finding of our study
is that zolpidem improved sleep characteristics at high altitude, inducing
a decrease in sleep onset latency (placebo, 22 +/- 12 min versus zolpidem,
10 +/- 6 min), an increase in SWS duration (placebo, 46 +/- 28 min versus
zolpidem, 69 +/- 28 min), and a reduction in the arousal index during SWS
(placebo, 7.4 +/- 4.1 per h versus zolpidem: 2.4 +/- 1.0 per h).
Furthermore, none of the respiratory parameters were significantly affected
by zolpidem in any sleep stage. In conclusion, zolpidem improved sleep
quality at high altitude without adversely affecting respiration.
