The Impact of Exercise on Sleep

The Impact of Exercise on Sleep

By: Krista Hoose

From a global standpoint, both attaining a sufficient amount of quality sleep and engaging in routine physical activity are ongoing public health concerns. From an individual perspective, the effects are apparent when one or the other, or sometimes both, are inadequate. When sleep deprived, there is no better way to describe it than it is just more difficult to function both cognitively and physically. Gone is the energy to engage in exercise. On the flip side, without exercise, one might feel sluggish, anxious, uncomfortable, and lack energy, compared to days or periods of time with regular exercise. Is there a correlation between exercise and sleep, and how can each be used to our advantage?

The National Sleep Foundation recommends 7-9 hours of sleep for adults ages 18-64 and 7-8 hours for ages 65+ (National Sleep Foundation, 2015). The body uses this time to develop memories and restore all body systems, which are both necessary for optimal health. About one third of adults report sleep-related issues, suggesting sleep is a pertinent topic that affects a large number of people (Kline, 2014). Because research has shown that exercise and sleep have a bidirectional relationship, exercise is an attractive non-pharmacological method to reduce sleep-related complaints. This simply means that exercise can potentially lead to better sleep and better sleep can promote a more active lifestyle during the day.

For many people, engaging in moderate-to-vigorous exercise during the day reduces the time it takes to fall asleep and also decreases wakefulness during the night. In addition, the benefits of exercise on weight loss can decrease symptoms of obstructive sleep apnea (OSA), which in 60% of cases is associated with obesity (Pacheco, 2021). In 2013, the National Sleep Foundation conducted a survey called the Sleep in America Poll concerning the sleep quality and habits of 1,000 participants ages 23-60. The study was conducted in order to evaluate the relationship between sleep and physical activity (National Sleep Foundation, 2013). Very good or fairly good sleep quality was reported in 76-83% of those who engaged in light, moderate, or vigorous exercise, compared to in 56% of those who did not engage in exercise (Pacheco, 2021). Looking at the impact of sleep on exercise, in general, those who experience less sleep are less active. This could be due to excessive daytime sleepiness or general fatigue from poor sleep.

There is no rule of thumb on the best time of day to exercise in order to improve sleep; it depends on the person. Exercising in the morning or afternoon causes a shift forward in the circadian rhythm by causing an earlier release of melatonin. Morning exercise done outside may also cause that same shift due to exposure to sunlight. Both result in being able to fall asleep earlier. Some people have difficulty sleeping if they exercise at night, while others experience no impact on sleep. As long as moderate-intensity exercise stops at least 90 minutes prior to bedtime, it often has no impact on sleep, since the body has enough time for endorphins and body temperature to decrease. Exercise also helps calm anxiety and decrease depression, which could have an impact on sleep. Some people even feel that sleep is improved after evening exercise, allowing them to fall asleep quicker and staying asleep through the night. Vigorous exercise within an hour of bedtime may decrease sleep quality, since the body does not have time to cool back down to temperatures ideal for sleep (Pacheco, 2021).

Because exercise at almost any time of the day has been shown to improve sleep, it is best to tailor your workout to the time that works best for you. If you need to establish an earlier bedtime, consider working out in the morning to fall asleep faster at bedtime. If you tend to have difficulty staying asleep, consider shifting your workout to later in the afternoon or early evening. Resistance training or light exercise may provide benefit in the evening, as they provide the benefits of physical activity without the rise in body temperature that would make sleeping conditions unfavorable. The converse is true; if you have difficulty sleeping at night, consider shifting your workouts earlier in the day (Pacheco, 2021). It would be intuitive to think that although exercise can improve sleep quality, it may not be the only answer. Consider your sleep hygiene practices that could be impacting sleep quality, such as inconsistent routines, electronic screen time, meal timing, and caffeine (Suni, 2020). More information about sleep hygiene best practices can be found at https://www.sleepfoundation.org/sleep-hygiene. If you have questions about your sleep duration and/or quality or about your routine, as always, consult a medical professional.