Exogenous Ketosis Improves Sleep Efficiency and Counteracts the Decline in REM Sleep after Strenuous Exercise

Ten well-trained cyclists with good sleep quality took part in a randomized crossover study with morning endurance training and evening high-intensity interval training, followed by overnight polysomnography. They received either 25 g of ketone ester or a placebo drink after exercise and 30 minutes before sleep, and a third session without exercise served as a rest comparison. Blood D-beta-hydroxybutyrate rose to about 3 mM with ketone ester. Exercise reduced REM sleep by 26 percent and increased wakefulness after sleep onset by 95 percent versus rest, and ketone ester improved sleep efficiency by 3 percent and counteracted both changes versus the exercise placebo.