Is it wiser to train in the afternoon or the early evening to sleep better? The role of chronotype in young adolescent athletes

Abstract

Study objectives To examine the effect of the timing of high-intensity exercise (afternoon vs. evening) on adolescent athletes’ bedtime psychological state, sleep quality, sleep staging, and next-day wellness/sleepiness according to chronotype. Methods Forty-two young athletes (morning type: n =12, intermediate type: n =14; evening type: n=16) completed a randomized crossover study under free-living conditions. The counterbalanced sessions include: (AEX) afternoon (1:00 – 3:00 pm) and (EEX) evening (5:30 – 7:30 pm) high-intensity exercise. Sessions were conducted over three days each and were separated by a 1-week washout period. The time in bed was fixed (10:30 pm – 7:30 am). Sleep was assessed through ambulatory polysomnography. Results The effect of high-intensity exercise on sleep differs significantly depending on the time of exercise with lower sleep efficiency: SE (-1.50%, p<0.01), and higher SOL (+4.60min, p=<0.01), during EEX vs. AEX. Contrary to the previous view, we discovered differences in the mediated response based on the chronotype of young athletes. These differences were observable in the psychological state at bedtime, objective sleep, and the next day's self-reported wellness. Whereas the sleep of participants with a late chronotype remains stable regardless of the time of exercise, those with early chronotype experience higher mood disturbances and clinically significant sleep disruptions following evening high-intensity exercise. Conclusions Exercise timing and chronotype affect the psychological state at bedtime and objective sleep in adolescent athletes. This also alters next morning signs of pre-fatigue and wellness which suggest that the consideration of both features is important to adolescent athletes’ recovery.

Effects of acute bouts of evening resistance or endurance exercises on sleep EEG and salivary cortisol

“…TST also tended to be lower following endurance exercise. Our results align with recent findings from Saidi and others ( Saidi et al, 2023 ) showing lower sleep efficiency (−1.50%) following high intensity evening exercise, although the intensity was moderate in the current study. Both endurance and resistance exercise conditions also led to greater theta power compared to the control condition during N2 sleep stage.…”

“…Seemly, Saidi and others investigated the effects of afternoon compare to evening exercise in young adolescent athletes and has shown that evening exercise led to lower sleep efficiency and longer sleep onset latency. Such effects were also moderated by chronotype (Saidi et al, 2023). Therefore, the effects of acute exercise performed in the evening is still controversial.…”

The effect of sleep restriction, with or without high‐intensity interval exercise, on behavioural alertness and mood state in young healthy males

“…The appropriate choice of when to exercise under sleep‐restricted conditions is another important consideration, given the potential time‐of‐day specific effects of exercise (Grgic et al, 2019; Saner & Lee, 2020) and considering that the influence of sleep restriction on mood and alertness, likely increases throughout the day. In this regard, a recent study demonstrated that individual chronotype was an important consideration for interpreting the effect of exercise timing on psychological state and sleep quality (Saidi et al, 2023). Although participants in the current study were classified as either moderate or intermediate chronotypes, this should be another consideration in future research.…”

Sleep Health, Individual Characteristics, Lifestyle Factors, and Marathon Completion Time in Marathon Runners: A Retrospective Investigation of the 2016 London Marathon

“…Unfortunately, this may result in athletes shortchanging sleep due to early AM or late PM training sessions. Furthermore, late PM training may lead to heightened pre-sleep arousal [ 6 , 22 ], which can translate into difficulties with sleep initiation. These factors highlight the augmented risk that marathoners are likely to face for poor sleep health.…”