[Quality of sleep and periodic breathing during sleep in healthy persons at a height of 3200 meters].

In order to investigate quality of sleep and sleep-related breathing disorders (SRBD) at high altitude we performed full polysomnography in 9 young healthy volunteers at lowland (760 m above see level) and on the 1st and 6th night after the ascent to the altitude of 3200 m. The subjects were non-smoking males aged 20.3 +/- 3.5 years with normal spirometry and arterial blood gas measurements performed at low altitude. We found no statistical difference in sleep quality between low and both nights at high altitude as considered by % of stages 1, 2, 3 + 4 non-REM, and REM sleep, total sleep time, sleep efficiency, and number of awakenings+arousals. There was no periodic breathing (PB) during sleep but some central events of SRBD at low altitude. PB appeared at high altitude mostly during non-REM sleep and remained stable throughout the study period. There were also some obstructive SRBD found during high altitude nights. Mean SaO2 was lower during both nights at high altitude when compared to low altitude (p < 0.00001). It was higher during the 6th than during the 1st night at altitude (p < 0.0001). Minimum SaO2 was comparable during low altitude and 6th night at altitude and was lower during the 1st altitude night (p < 0.02). We conclude that sleep quality at the altitude of 3200 m remains unchanged when compared to lowland. There is high individual variability in PB at altitude and its intensity is negligible.