High altitude exposure impairs sleep patterns, mood, and cognitive functions.

This work evaluated the importance of sleep on mood and cognition after 24 h of exposure to hypoxia. Ten males, aged 23-30 years, were placed in a normobaric chamber simulating an altitude of 4,500 m. Sleep assessments were conducted from 22:00-6:00; all mood and cognitive assessments were performed 20 min after awakening. The assessments were conducted in normoxic conditions and after 24 h of hypoxia. Sleep was reevaluated 14 h after the start of exposure to hypoxic conditions, and mood state and cognitive functions were reevaluated 24 h after the start of exposure to hypoxic conditions. Hypoxia reduced total sleep time, sleep efficiency, slow-wave sleep, and rapid eye movement. Depressive mood, anger, and fatigue increased under hypoxic conditions. Vigor, attention, visual and working memory, concentration, executive functions, inhibitory control, and speed of mental processing worsened. Changes in sleep patterns can modulate mood and cognition after 24 h.

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