Short half-life hypnotics preserve physical fitness and altitude tolerance during military mountainous training.
OBJECTIVE
We study the effect of short half-life hypnotics (zaleplon or zolpidem against placebo) on altitude tolerance in 12 nonacclimated male soldiers (age, 22.1 +/- 0.8 years; height, 177.8 +/- 1.7 cm; weight, 69.8 +/- 1.7 kg).


METHODS
Soldiers were trained to practice mountaineering at high altitude (2,533-4,810 meters) during 3 periods (one per medication tested) of 4 days (D1-D4). In each period the nights were spent in a hut (3,613 m). Administration of hypnotics or placebo was then implemented at 9:45 p.m. Nocturnal arterial oxygen saturation (SaO2) and heart rate variability (HRV) were monitored. At 5:00 a.m. and 9:00 p.m. physical fitness was assessed using acute mountain sickness (AMS) score. At 5:00 p.m., a posteffort stand test was carried out to evaluate the orthoparasympathetic imbalance with fatigue.


RESULTS
Nocturnal SaO2 correlated negatively with morning AMS scores (R = -0.820, p < 0.02) and HRV analysis favored the sympathetic modulation. Posteffort stand tests revealed that sympathetic modulation attenuated from D2 to D3 in treated groups.


CONCLUSIONS
The present study provides evidence that zolpidem or zaleplon improves sleep and subsequent physical fitness at altitude.
Jouanin
Jean-claude
JC
Department of Aerospace Physiology, Institute of Aerospace Medicine of the Army Health Department, BP 73, 91223 Brétigny-sur-Orge Cedex, France.
Dussault
Caroline
C
Van Beers
Pascal
P
Piérard
Christophe
C
Beaumont
Maurice
M
D000081:Acetamides / Q000008:administration & dosage / Q000493:pharmacokinetics*; D000532:Altitude Sickness / Q000517:prevention & control*; D000704:Analysis of Variance; D006207:Half-Life; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage / Q000493:pharmacokinetics*; D016014:Linear Models; D008297:Male; D008889:Military Personnel; D009051:Mountaineering / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D011725:Pyridines / Q000008:administration & dosage / Q000493:pharmacokinetics*; D011743:Pyrimidines / Q000008:administration & dosage / Q000493:pharmacokinetics*; D013557:Switzerland; D055815:Young Adult; D000077334:Zolpidem
D000081:Acetamides; D006993:Hypnotics and Sedatives; D011725:Pyridines; D011743:Pyrimidines; D000077334:Zolpidem; C085665:zaleplon