Improving adaptation in male high-altitude workers through pressurization: a randomized controlled trial on sleep architecture.

BACKGROUND: Sleep disruption at high altitude, driven by hypobaric hypoxia, is prevalent among occupational cohorts and adversely affects health, safety, and cognitive performance. While oxygen supplementation improves nocturnal hypoxia, it does not replicate the integrated physiological stimulus of true altitude descent. This study investigated the effects of simulated, stepwise altitude descent via nocturnal pressurization on sleep in acclimatized workers residing at high altitude. METHODS: In a 5-week randomized controlled trial, 24 male workers residing at 3500 m were allocated to a Pressurization group (n = 12) or a Control group (n = 12). The Pressurization group slept in a pressurized environmental simulator at sequentially lower simulated altitudes (3000 m, 2500 m, then 2000 m) over three weeks, while both groups worked at 3500 m during the day. The Control group remained at ambient 3500 m throughout. Sleep architecture and nocturnal oxygen saturation (SpO₂) were monitored weekly. Linear mixed-effects models assessed the effects of Group, Time, and their interaction. RESULTS: A significant Group × Time interaction was observed for nocturnal oxygenation (Mean SpO₂: F(4,88) = 28.36, p < 0.001; Minimum SpO₂: F(4,88) = 7.16, p < 0.001). The Pressurization group showed dose-dependent increases in Mean and Minimum SpO₂, peaking at the 2000 m simulated altitude. Concurrently, the Pressurization group exhibited a significant increase in deep sleep percentage at 2000 m (Group × Time effect: 3.25%, p = 0.010) and a marked reduction in the arousal index (ArI) at 2500 m and 2000 m (- 5.42 and - 7.01 events/h, respectively, p < 0.001). Epworth Sleepiness Scale scores also decreased significantly in the Pressurization group during descent (p < 0.01). No significant changes were observed in total sleep time, Rapid Eye Movement sleep, or wake time percentage. CONCLUSION: Nocturnal pressurization simulating stepwise descent to lower altitudes significantly improves nocturnal oxygenation, consolidates deep sleep, reduces sleep fragmentation, and alleviates daytime sleepiness in high-altitude workers. This intervention, which mimics the combined barometric and hypoxic stimulus of true descent, presents a distinct and promising non-pharmacological strategy for managing sleep disturbances in occupational settings at high altitude.