Abstract des Autors

This paper presents a review on the effects of exercise on sleep and vice versa, in order to examine whether slow wave sleep is responsible for body restitution. First, the stages of vigilance, i.e. wakefulness, sleep (stages 1, 2, 3, 4) and paradoxical sleep (REM sleep), are described from the data obtained through polysomnographic recordings.

Restorative theories of sleep are based on the occurrence of growth hormone secretion during slow wave sleep (SWS: stages 3 and 4) and on the early finding of increased SWS in athletes. However, these theories are discussed, as many experimental results do not agree with their implications.

Sleep deprivation studies have shown that physical exercise has little effect on recovery sleep quality, fatigue perception, mood or mental performance. Also, prolonged wakefulness does not affect the characteristics of the exercise. The only influence lies on the slow recovery processes occurring upon cessation of the exercise.

SWS modifications after exercise are not consistant. SWS is increased in young athletes exercising in the afternoon, but the increase may lack if the exercise intensity is not large enough, or in older people, or in young sedentary subjects. Also, REM sleep may be affected as a result of the stress induced by exercise. Sleep organisation may also be disturbed, as a stress reaction.

One consistant finding is that heart rate is increased throughout the night sleep following diurnal physical exercise. This is certainly due to a persistant increase in metabolic rate. In fact, when it occurs, the increase in SWS after physical exercise is related to the enhanced heat content of the body due to muscular work. Recent experiments have shown that SWS is also increased after passively induced hyperthermia, while body cooling during exercise in athletes prevents any variation in SWS to occur. In conclusion, sleep does not seem to be necessary for body restitution, as the thermoregulatory mechanisms controlled by the hypothalamus are susceptible to explain sleep variations after physical exercise.

Abstract des Autors

La fonction du sommeil à ondes delta est toujours discutée. Les théories restauratrices du sommeil, nées dans les années 70, lui attribuent un rôle dans les processus de récupération de la fatigue physique. Cependant, les arguments en faveur de ces théories sont controversés à partir de faits expérimentaux relevés lors de l'étude des relations entre l'absence prolongée de sommeil et l'exercice physique et entre l'exercice et les états de sommeil.

L'exercice physique ne modifie pas les effets de la privation de sommeil sur la fatigue, l'humeur et les performances mentales. Inversement, l'éveil prolongé n'affecte pas les caractéristiques de l'exercice, mis à part les processus de récupération lente immédiate. Une augmentation du sommeil delta survient chez des athlètes jeunes à la suite d'un exercice physique réalisé dans l'après-midi, alors que l'exercice effectué plus tard dans la soirée induit une baisse du sommeil paradoxal. Cependant, ces réactions ne sont pas constantes. Au contraire, une tachycardie nocturne persistante est toujours observée après un exercice diurne. Elle est sans doute liée à l'augmentation persistante du métabolisme. En fait, l'hyperthermie induite par le travail musculaire semble être responsable de l'augmentation du sommeil delta observée chez les athlètes.