A Single Night in Hypoxia Either with or without Ketone Ester Ingestion Reduces Sleep Quality without Impacting Next-Day Exercise Performance

Eleven healthy male participants completed three sessions with normoxic training followed by sleep in normoxia or at a simulated altitude of 3000 m, receiving either ketone ester or placebo after exercise and before sleep. Sleep was recorded by polysomnography and next-day performance was a 30-minute all-out time trial. Hypoxia caused about a 3 percent drop in sleep efficiency, with doubled wakefulness after sleep onset and about a 22 percent reduction in slow wave sleep. Ketone ester eased the gradual drop in SpO2 early in the night but did not alter the hypoxia-induced sleep changes, and neither ketone ester nor hypoxia affected time trial performance, although hypoxia hampered heart rate recovery after the trial.