- By matnedelec
- On 15/01/2020
Evening work-out or a good night’s sleep: do we really have to choose?
Monday night, 10:30pm in Paris. As one of January’s cold snaps hits me, I walk home as briskly as possible. When turning a corner, I am attracted by a particularly bright window. As I get closer, a loud and catchy song becomes clearer to me. A gym! Behind the window, a dozen athletes are trying to keep up with the coach’s pace. A barely visible drop of sweat is running down his forehead, and he has the decency at the end of the class not to tell his students that it is his seventh class of the day… This ordinary urban event is the opportunity to answer one of the most frequently asked questions during my interventions: “does evening exercise disrupt my sleep?”.
Medical doctors and public opinion generally tend to discourage intense evening exercise, during the period leading to bedtime. Such an exercise would impair the quality of sleep during the following night. Today, there is very little proof in scientific literature to support the evening sofa option rather than outdoor running or on a treadmill in the gym. In 1976, Browman and Tepas certainly showed an increase in sleep onset latency - or the time required to fall asleep - following late-night exercise. The significant increase in sleep onset latency was of 6 minutes after a 45-min cycling session performed only five minutes prior to bedtime! As fast as you may be to shower, go home and enjoy a little snack, we can bet that the recovery period between the end of your session and bedtime is longer… Several studies have shown the lack of effect or even positive changes on sleep from an evening exercise. For example, Buman et al. (2014) have shown, in a large cohort of 1 000 adults, that fans of evening exercise - performed less than 4 hours before bedtime - display a similar sleep or a better sleep on exercising days compared to resting days. What’s more, a meta-analysis gathering the results of almost 3 000 adults concluded that exercising less than 3 hours prior to bedtime is beneficial for sleep, i.e. less wake after sleep onset and less light sleep throughout the night (Kredlow et al., 2015). And what about exercise intensity? Performing an exercise subjectively perceived as difficult one and a half hours before bedtime is associated with better sleep quality and a reduction in sleep onset latency (Brand et al., 2014).
Our core body temperature follows a circadian rhythm, very close to 24 hours. It is at its lowest around 3:00 or 4:00am and increases progressively before peaking between 6:00 and 8:00pm. Between these hours, is the ideal window to outdo your personal record! Sleep initiation is then linked to a decrease of your core temperature (approximately 0.5 to 1°C) and deep sleep is made more possible during the first part of the night if our core body temperature is reduced. The general advice of not exercising in the evening is mainly based on the assumption that evening exercise, especially if intensely performed, will increase core body temperature and threaten sleep quality. Reality is much more complex. To see clearer, we studied the influence of a high-intensity trail undergone in the lab at 9:00pm on well-trained runners’ sleep assessed by polysomnography (maximal aerobic speed superior to 18 km/h and VO2max of 70mL/min/kg). Results showed a slight change in sleep architecture during the night after exercising compared to the control condition. Core body temperature and heart rate were significantly increased throughout the first part of the night compared to the control condition. Another article which was published at the same time (Thomas et al., 2019) showed that an intermittent running exercise (6 sets of 5 minutes at 90% VO2peak; and 5 minutes recovery) at 6:00pm increased total sleep quantity during the subsequent night, even though an increase in heart rate was also observed.
It seems that evening exercising and a good night’s sleep are compatible! Regular physical activity paves the way to good sleep and long-term health. In order to maximise your chances, here is my list of strategies to favour your sleep after exercising in the evening:
1. Limit light exposition, especially to screens, and possibly wear tinted glasses.
2. Choose a milky beverage over water to ensure rehydration
3. Eat a high glycemic-index snack
4. Drink tart cheery juice and food rich in tryptophan (e.g. turkey, pumpkin seeds)
5. Set up an adequate sleeping environment: cool (18 to 19°C), peaceful and dark
6. Try out breathing exercises, which we will discuss next time
Mathieu Nedelec, sport scientist in charge of research projects on sleep and recovery. I teach best practices to improve sleep and performance. I will read your answers carefully and let you know when my next posts will be published.