Does practicing physical activity in the evening prevent you from sleeping well ? A new study answers the question

Faire de l’exercice en soirée empêche-t-il de bien dormir ?

Researchers in sleep physiology from the University and Caen University Hospital explored the effects of physical activity in the evening on sleep. Result: as a precaution, it is better to avoid physical activity just before sleeping.

While there is often no other way than to devote time to physical activity in the evening, after a day of work, research warns against deleterious effects of late physical activity on sleep. This time, French researchers studied the quality and quantity of sleep in young athletes after exercising before bed. Their results confirm that evening exercise could lead to a level of neurophysiological arousal that could disrupt sleep.

Endurance exercises more harmful than resistance exercises ?

This study of 16 healthy young athletes, aged 21 to 27, used polysomnographic recordings (measurements of brain activity, movement and breathing) and salivary cortisol levels. The two types of exercise, endurance (using cardiorespiratory capacities, regular but light muscle contractions) or resistance (using muscular strength, rarer but strong muscle contractions), were carried out 1 hour before the lie down for 30 minutes. Ultimately, endurance and resistance exercise resulted in impaired sleep quantity and quality, with reduced sleep efficiency following endurance exercise.

An adaptation of brain activity following physical exercise

Analyses of spectral power by electroencephalography (which records electrical activity on the surface of the brain) revealed an increase in alpha and theta power (electrical signals produced by the brain) during certain sleep phases after both types of exercise. These increases could reflect adaptive changes in nighttime brain activity in response to exercise.

But the two types of exercise produced different impacts. Endurance exercise resulted in increased brain activity (beta spectral power) and elevated cortisol levels, suggesting hyperarousal. Resistance is associated with less brain activity and lower cortisol levels. In summary: endurance exercises have a greater negative impact on sleep neurophysiology.

But be careful, although the study shows changes in sleep after nocturnal exercise, it does not consider these effects to be truly deleterious, a point that remains to be explored. For Joy Perrier, post-doctoral student at the University of Caen, first author of the study, "these results provide valuable insight into the physiological effects of physical exercises performed in the evening and confirm the warnings to avoid physical activity if possible late in the evening and less than 2 hours before bedtime". Precautionary principle.

Note: an increase in alpha power after evening exercise may indicate greater environmental awareness during light sleep. Additionally, an increase in theta power during light sleep may be linked to memory processes, suggesting that moderate exercise may influence cognitive processes during sleep (not tested in this study).