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

Impairments in cognitive function, mood, and sleep quality occur following
ascent to high altitude. Low oxygen (hypoxia) and poor sleep quality are
both linked to impaired cognitive performance but their independent
contributions at high altitude remain unknown. Adaptive servoventilation
(ASV) improves sleep quality by stabilizing breathing and preventing
central apneas without supplemental oxygen. We compared the efficacy of
ASV and supplemental oxygen sleep treatments for improving daytime
cognitive function and mood in high-altitude visitors (N = 18) during
acclimatization to 3,800 m. Each night, subjects were randomly provided
with ASV, supplemental oxygen (SpO₂ > 95%), or no treatment. Each
morning subjects completed a series of cognitive function tests and
questionnaires to assess mood and multiple aspects of cognitive
performance. We found that both ASV and supplemental oxygen (O2) improved
daytime feelings of confusion (ASV: p < 0.01; O₂: p < 0.05)
and fatigue (ASV: p < 0.01; O₂: p < 0.01) but did not
improve other measures of cognitive performance at high altitude. However,
performance improved on the trail making tests (TMT) A and B (p <
0.001), the balloon analog risk test (p < 0.0001), and the
psychomotor vigilance test (p < 0.01) over the course of three days
at altitude after controlling for effects of sleep treatments. Compared to
sea level, subjects reported higher levels of confusion (p < 0.01)
and performed worse on the TMT A (p < 0.05) and the emotion
recognition test (p < 0.05) on nights when they received no
treatment at high altitude. These results suggest that stabilizing
breathing (ASV) or increasing oxygenation (supplemental oxygen) during
sleep can reduce feelings of fatigue and confusion but that daytime
hypoxia may play a larger role in other cognitive impairments reported at
high altitude. Furthermore, this study provides evidence that some aspects
of cognition (executive control, risk inhibition, sustained attention)
improve with acclimatization.