RESUMO
OBJECTIVE: To explore how hypoxia circumstance affects sleep architecture and to study the potential use of oxygen enrichment of room air at an altitude of 3700 m. METHODS: Oxygen concentration was raised to (24.30 +/- 0.88)% in a room with a dimension of 4.51 m x 3.32 m x 3.41 m. Twelve men aged 18 to 20 years who had stayed at high altitude (3700 m above sea level) for 30 days slept one night in a room of ambient air and another night in the oxygen enriched room the order being randomized. Their electroencephalograms (EEG) were recorded with CFM-8 polysomnography. RESULTS: Significantly more time was spent in deep sleep (stages III and IV combined, also known as slow-wave sleep) with oxygen enriched than ambient air [(19.33 +/- 4.85)% vs (13.67 +/- 3.75)%, P < 0.01 with paired comparisons]. The total sleep time [(500.83 +/- 32.94) min vs (470.67 +/- 27.43) min, P < 0.05] and the efficient sleep index [(90.33 +/- 2.06)% vs (85.50 +/- 3.34)%, P < 0.001] were increased in oxygen enriched air. No differences between ambient and oxygen enriched air were found in sleep latency the time to fall asleep, the number of arousal and sleep shift (the time spent awake after falling asleep), but there was a trend toward fewer of these with oxygen treatment. CONCLUSIONS: Installing an oxygen-enriched room at high altitude is relatively simple and inexpensive, and there will be a promise for improving sleep quality, well-being, and work capacity.
