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

## TL;DR

This study found that pre-existing insomnia symptoms predict the risk of acute mountain sickness during high-altitude climbs.

## Contribution

The study identifies baseline insomnia symptoms as an independent predictor of acute mountain sickness in high-altitude expeditions.

## Key findings

- Baseline Athens Insomnia Scale scores were independently associated with acute mountain sickness risk.
- Ten out of fifteen participants developed acute mountain sickness with a mean Lake Louise Score of 4.3.
- High-altitude insomnia scores did not remain a stable predictor after adjusting for age and gender.

## Abstract

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.

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.

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).

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.