An Intensified Training Period Reduces REM Sleep but this Decline Can Be Mitigated by Ketone Ester Supplementation

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.

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.

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<0.001, Hedges' g = 1.097). From PRE to MID, sleep efficiency improved by 3% in both groups (p=0.003, Hedges' g = 0.663) while wakefulness after sleep onset reduced by 2% (p=0.031, Hedges' g = 0.716). However, from PRE to POST, total REM sleep decreased by 2% in CON but increased by 3% in KE (p=0.002, for KE vs. CON, Hedges' g = 0.939). Perceived sleep quality did not differ between groups throughout the intervention.

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.