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

INTRODUCTION: Available evidence indicates that ketone bodies may improve sleep quality. Therefore, we determined whether ketone ester (KE) intake could counteract sleep disruptions induced by strenuous exercise. METHODS: Ten well-trained cyclists with good sleep quality participated in a randomized crossover design consisting of two experimental sessions each involving a morning endurance training and an evening high-intensity interval training ending 1 h before sleep, after which polysomnography was performed overnight. Postexercise and 30 min before sleeping time, subjects received either 25 g of KE (EX(KE)) or a placebo drink (EX(CON)). A third session without exercise but with placebo supplements (R(CON)) was added to evaluate the effect of exercise per se on sleep. RESULTS: Blood d-β-hydroxybutyrate concentrations transiently increased to ~3 mM postexercise and during the first part of the night in EX(KE) but not in EX(CON) or R(CON). Exercise significantly reduced rapid eye movement sleep by 26% (P = 0.001 vs R(CON)) and increased wakefulness after sleep onset by 95% (P = 0.004 vs R(CON)). Interestingly, KE improved sleep efficiency by 3% (P = 0.040 vs EX(CON)) and counteracted the exercise-induced decrease in rapid eye movement sleep (P = 0.011 vs EX(CON)) and the increase in wakefulness after sleep onset (P = 0.009 vs EX(CON)). This was accompanied by a KE-induced increase in dopamine excretion (P = 0.033 vs EX(CON)), which plays a pivotal role in sleep regulation. In addition, exercise increased sleep spindle density by 36% (P = 0.005 vs R(CON)), suggesting an effect on neural plasticity processes during sleep. CONCLUSIONS: These data indicate that KE ingestion improves sleep efficiency and quality after high-intensity exercise. We provide preliminary evidence that this might result from KE-induced increases in dopamine signaling.