The quality of sleep and periodic breathing in healthy subjects at an altitude of 3,200 m.

The medical risks of travel and stay at high altitude are well known. Many more people travel for recreation to lower but still significant altitudes. To investigate the quality of sleep and sleep-related breathing disorders (SRBD) at that altitude we performed full polysomnography in nine young volunteers at lowland (760 m above sea level) on the first and sixth night after ascent to 3,200 m. There have been few studies on such populations. The subjects were nonsmoking healthy males aged 20.3 +/- 3.5 years with normal spirometry and arterial blood gas measurements performed at low altitude. Although there was no statistically significant difference in the duration of stages and sleep quality between low altitude night and both nights at high altitude as assessed by percent of sleep spent in stage 1, 2, 3+4 NREM, and REM sleep, total sleep time (TST), and sleep efficiency; the number of arousals and awakenings doubled at high altitude. There was no periodic breathing (PB) during sleep, except in isolated central events of SRBD, at low altitude. PB appeared at altitude mostly during NREM sleep and its intensity remained stable throughout the study period. Individual variations of PB intensity were high, ranging from 0.1 to 24% of TST. There were also some episodes of obstructive apnea and hypopnea during sleep at high altitude (p < 0.001). Mean SaO2 was lower during the study nights at high altitude when compared with low altitude. There were some signs of ventilatory acclimatization as shown by a higher mean SaO2 during the sixth compared with the first night at altitude (p < 0.001). We conclude that the sleep quality at the altitude of 3,200 m remains satisfactory when compared to low altitude. There is high individual variability in intensity of PB at that altitude.

[Quality of sleep and periodic breathing during sleep in healthy persons at a height of 3200 meters]. / Jakosc snu oraz oddychanie okresowe podczas snu u ludzi zdrowych na wysokosci 3200 metrów.

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.