The independent predictive effect of insomnia symptoms before high-altitude exposure on acute mountain sickness:an observational study of healthy volunteers at 2726 m

Abstract

Objective: To examine the independent predictive role of symptoms of insomnia on the risk of acute mountain sickness (AMS) in healthy volunteers during a short-term extreme-altitude mountaineering activity. Methods: Fifteen healthy volunteers were recruited for a 3-day mountaineering expedition with a target altitude of 5,396 meters. Baseline symptoms of insomnia were assessed one week before departure at low altitude (Wuhan, 23 m) using the Athens Insomnia Scale (AIS). During the 3-day ascent, high-altitude insomnia symptoms and AMS symptoms were evaluated daily using the AIS and the 2018 Lake Louise Score (LLS), respectively. The primary analysis for AMS, based on LLS assessment (Day 2 post-arrival), was conducted at an altitude of 2726 m. Univariate and multivariate logistic regression analyses were conducted to examine the association between AIS scores and AMS. Results: The mean baseline AIS score of participants was 6.9, and the mean high-altitude AIS score was 10.7. During the expedition, AMS (defined as LLS≥3) occurred in 10 participants, with a mean LLS score of 4.3 among AMS cases. Univariate analysis showed that both baseline AIS score (OR = 2.994,95%CI:1.059–8.459, p<0.05) and high-altitude AIS score (OR=3.901,95% CI: 1.124–13.544, p<0.05) were significantly positively associated with AMS risk. In multivariate analysis, after adjusting for age and gender, baseline AIS score remained an independent predictor of AMS (OR = 3.074, 95% CI:1.023–8.638, p<0.05), whereas the high-altitude AIS score did not yield a stable estimate due to complete separation in the model. Univariate analysis indicated that ΔAIS (change in AIS score) did not show a significant effect on AMS (p>0.05). Conclusion: Baseline AIS scores serve as an independent predictor of AMS, supporting the incorporation of sleep assessment into pre-ascent. health screening for high-altitude mountaineering. However, this finding is derived from a small sample within a specific cohort; its predictive utility and generalizability must be independently validated in future studies with larger and more diverse populations.