AMBULATORY SLEEP-WAKE RECORDING IN AN ACCLIMATIZED MOUNTAINEER OVER 8DAYS AT HIGH-ALTITUDE

Continuous ambulatory polygraphy (electroencephalogram and electroocul ogram) was recorded on a 34-year-old female mountaineer acclimatized t o an altitude of 5350 m, using a portable Oxford Medilog 9000 cassette recorder over 8 consecutive days. The recordings at altitudes of 5000 to 7600 m were performed while attempting to climb Mount Everest with out an oxygen mask. The subject slept only at night. Altitude sleep me asures were compared to data obtained at 300 m altitude during one 24- h recording performed before the expedition departed. The sleep-wake o rganization was barely influenced by altitude. Intrasleep wakefulness was augmented, leading to a decrease in sleep efficiency. No slow-wave -sleep curtailment was found, and day-to-day sleep-wake variations wer e more likely due to anxiety, fatigue owing to strenuous effort, night time cold, or daytime heat exposure.