Cognitive function and mood at high altitude following acclimatization and use of supplemental oxygen and adaptive servoventilation sleep treatments

Fig 1. AMS scores decrease over three days at high-altitude. Points indicate daily AMS scores for each individual. Means and 95% confidence intervals are provided for each day. Asterisks indicate significant differences across days at p < 0.05 (*) and < 0.001 (***). A score of 3–5 indicates mild AMS and ≥ 6 indicates severe AMS.

Fig 2. ASV and supplemental oxygen sleep treatments decrease fatigue and confusion. Results of post-hoc Tukey HSD tests on two-way ANOVA tests examining independent effects of sleep treatment on fatigue and confusion within subjects. Means and 95% confidence intervals for each treatment group are provided. Asterisks indicate significance at p < 0.05 (*) and p < 0.01 (**).

Fig 3. Performance on TMT A and B improved following acclimatization. Performance was worst (longer duration to complete task) on day 1 at altitude (A, C). TMT A scores were better at sea level than high altitude (B) but TMT B scores were not significantly impaired after ascent to high altitude (D). Means and 95% confidence intervals are provided. Asterisks indicate significant differences across groups at p < 0.05 (*), p < 0.01 (**), and p< 0.001 (***). SL = sea level, HA = high altitude.

Fig 4. Altitude effects on emotion recognition. The total number of correctly identified expressions over three days at high altitude. Subjects were presented with happy, sad, angry, fearful, and neutral expressions. Means and 95% confidence intervals for each day are presented. Asterisks indicate significant differences across days at p < 0.05 (*), p < 0.01 (**), and p < 0.001 (***).

Fig 5. Risk-taking behavior identified by the BART decreases after acclimatization. The total number of pumps (A), mean number of pumps (D), total reward collected (B), mean reward collected (E), mean reaction time before each pump (C), and median reaction time before each pump (F) decreased over three days at high altitude. Means and 95% confidence intervals are presented. Asterisks indicate significant differences across days at p < 0.05 (*), p < 0.01 (**), and p < 0.001 (***).

Fig 6. Effects of altitude on ANT performance. Alert, Orienting, and Conflict Effect scores on the ANT over three consecutive days at high altitude (top panels) and at sea level (SL) compared to the no-treatment night at high altitude (HA, bottom panels). Means and 95% confidence intervals are presented for each group. Asterisks indicate significant differences across days or locations at p < 0.05 (*).

Fig 7. Errors and false starts on the PVT decrease following acclimatization. Errors and false starts decreased over three days at high altitude, resulting in higher aggregate scores on day 3. Mean reaction times did not decrease significantly with acclimatization. Means and 95% confidence intervals are provided for each day. Asterisks indicate significant differences across days at p < 0.05 (*), p < 0.01 (**), and p < 0.001 (***).