Short-term descent to low altitude reduces sleep-disordered breathing in moderate-altitude residents
A randomized crossover trial in 44 healthy adults living above 1000 m found that a brief stay at low altitude (590 m) significantly reduced nocturnal oxygen desaturation and breathing disorders compared to sleeping at their home altitude.
Researchers studied 44 healthy adults (median age 47, 50% female) living at moderate altitude (median 1230 m) in a randomized crossover design. Participants underwent two consecutive nights of sleep monitoring at their home elevation and two nights at a sleep laboratory in Chur, Switzerland (590 m), with a 2-week washout between conditions.
Time spent with oxygen saturation below 90% (T90) was significantly lower at low altitude: 1 ± 2 minutes at 590 m versus 5 ± 2 minutes at home altitude (mean difference 4 min, p = 0.005). The apnea-hypopnea index (AHI, a measure of breathing disruptions) was 9.2/h at low altitude and 14.2/h at home altitude; notably, 13.6% of participants showed severe SDB (AHI > 30/h) at home altitude compared to 2.3% at low altitude (p = 0.025). Oxygen desaturation index decreased from 10.0/h at home to 6.0/h at low altitude, and average nighttime oxygen saturation improved from 93.8% to 95.2% (p < 0.001). Slow-wave sleep was higher at low altitude (10.0% versus 8.0%, p = 0.001). The effect was larger in males, who showed a 7-minute reduction in T90 and a 4% increase in REM sleep at low altitude, whereas females showed smaller changes. A key limitation is that the study included only healthy residents; effects may differ in people with existing sleep or pulmonary conditions.
The sex difference is striking: males benefited more from altitude descent, with a 7-minute reduction in hypoxemia time and 4% greater REM sleep, while females showed modest changes—this hints that physiological adaptation or sensitivity to altitude may differ by sex, though the mechanism remains unclear. The study was conducted in a controlled crossover design, strengthening causal inference, but participants were all healthy; people with pre-existing pulmonary or cardiac disease might respond differently. The clinical implication is significant: sleep labs at lower elevations than a patient's home could systematically underdiagnose sleep apnea in the ~100 million people worldwide living above 1000 m, particularly men. The magnitude of effect is clinically meaningful—a shift from 13.6% to 2.3% prevalence of severe apnea represents a substantial drop in diagnostic categorization, not just a marginal change.
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Open in Cadence →References
- The effect of short-term descent to low altitude in healthy residents at moderate altitude - a randomized crossover trial. — Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine (Read the original)
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