An Intensified Training Period Reduces REM Sleep but this Decline Can Be Mitigated by Ketone Ester Supplementation.
Poffé C, Lauriks W, Stalmans M, Robberechts R. · Medicine and science in sports and exercise · 2026
Introduction: We previously showed that a strenuous training day disrupts sleep efficiency and REM sleep, and that these disturbances can be counteracted by ketone monoester (R)-3-hydroxybutyl-(R)-3-hydroxybutyrate (KE) supplementation. However, the impact of prolonged intensified training on sleep quality, as well as the potential modulating effect of KE are unknown.
Methods: We performed a double-blind study in which twenty-four trained male athletes completed a 7-week training program with a gradual increase in training load while receiving either 25g of a control drink (CON, n=12) or 25g of KE (n=12) after each training session and 30 minutes before sleep. At the start (PRE), week 3 (MID), and the end (POST) of the training program, we evaluated sleep using polysomnography, and perceived stress/recovery balance using the REST-Q questionnaire. Timing, duration, and relative intensity of exercise on each testing day were identical.
Results: The progressive increase in training load induced a decrease in the perceived stress-recovery state in both groups (PRE: 73±21 vs. POST: 40±37, p
Conclusions: Our data indicate that KE supplementation did not enhance the beneficial effect of an initial increase in training load on sleep but prevented the decline in REM sleep upon a further training load increment.