Most experts agree that exercise is an important part of sleep hygiene. Regular exercise, and even short bouts of exercise, lead to improvements in total sleep time, sleep quality, and time spent falling asleep. Exercise may also help reduce the symptoms of sleep disorders such as sleep apnea or sleep-related movement disorders.
Despite the clear benefits of exercise for sleep, there is ongoing debate about the best time of day to exercise for optimal sleep. Studies on the relationship between exercise timing and sleep have been carried out in a wide range of populations, making it difficult to draw clear conclusions. However, researchers are gradually starting to understand the different advantages of exercising at certain times of day.
What’s the Best Time of Day to Exercise for Better Sleep?
Current science suggests there is no one universal time of day that is best to exercise for sleep. Rather, the optimal exercise time likely depends on individual factors such as your chronotype, your age, and any underlying health conditions.
To see meaningful benefits for sleep, most experts recommend getting at least 150 minutes of exercise a week which should be 30 minute for five days a week. Research suggests that total sleep duration only increases after workouts of at least an hour, though this may depend on the type of exercise.
Individuals with pre-existing health conditions may need to approach exercise timing differently. For example, people at risk of high blood pressure may see greater improvements to sleep quality and nighttime blood pressure after exercising in the morning.
Exercise and the Circadian Rhythm
Aerobic exercise in the morning or the afternoon stimulates earlier melatonin release and shifts the circadian rhythm forward. For people who exercise outdoors, morning exercise may have the added benefit of exposure to sunlight. This helps entrain circadian rhythms and makes it easier to fall asleep early.
Research has found that evening exercise may negatively affect sleep quality for early birds, but not for night owls. This may be one reason why certain people have no trouble exercising at night, whereas others struggle to sleep afterward.
In one of the few studies that allowed participants to keep their regular exercise routine during the study instead of assigning a new one, there was no significant effect found on sleep quality for people who exercised in the morning versus the evening. It may be that we are naturally inclined to exercise at a time of day that fits well with our personal chronotype.
For professional athletes and others who are not able to choose their training schedule, taking melatonin after an evening exercise session may help reset the circadian rhythm and mitigate the effects on sleep quality.
Does Late Night Exercise Affect Sleep?
For most people, moderate-intensity exercise does not have a detrimental effect on sleep as long as it stops at least 90 minutes before bedtime. This allows time for endorphin levels and core body temperature to return to levels that are favorable to sleep.
In preparation for bedtime, our body temperature drops, our heart rate slows, and our brain waves get slower. By contrast, exercise leads to a rise in core body temperature, an increased heart rate, and higher levels of arousal that are not conducive to sleep. Following this logical train of thought, for many years, experts advised against exercising before bed.
However, recent studies have found that exercise at night may not have such a negative impact on sleep or morning grogginess, and may even increase the proportion of restorative deep sleep. The 2013 National Sleep Foundation Sleep in America Poll also found no evidence that evening exercise was harmful to sleep, and updated sleep hygiene recommendations to reflect the beneficial effects of exercise for sleep at any time of day.
Exercise helps calm anxiety and depression, and helps the mind relax in preparation for sleep. It also provokes a sharp rise in body temperature followed by a gradual cooling, which mimics the natural fluctuations of the circadian rhythm and paves the way for sleep. Multiple studies have found that evening exercise improves sleep quality by helping people fall asleep faster, reducing nighttime awakenings, and increasing the time spent in slow-wave sleep.
However, experts caution that vigorous exercise within one hour of bedtime doesn’t allow time for core body temperature to cool. This may delay sleep, affect sleep quality, and provoke more nighttime awakenings. To be safe, people with insomnia are usually advised to stick to light-to-moderate exercise at least four hours before bedtime.
How to Schedule Exercise to Improve Sleep
Both morning and evening exercise have been shown to promote deep sleep, and it appears that total sleep time is not affected by exercising in the morning versus the evening. However, you may be able to maximize the benefits for sleep by tailoring your exercise schedule to your personal needs.
Doing either aerobic (such as running) or resistance (such as weight-lifting) exercise in the morning can help you fall asleep faster at night. High-intensity exercise in the afternoon and early evening may also promote sound sleep. Working out at this time of day seems to contribute to drowsiness by lowering levels of orexin, a neurotransmitter that promotes wakefulness.
If you have no problems falling asleep but you find yourself frequently waking up throughout the night, you may find it more useful to add an evening exercise routine. Resistance exercise or light aerobic exercise performed in the early evening are best for reducing nighttime awakenings, possibly because they impart the benefits of exercise without excessively raising body temperature.
You may need to experiment to find an exercise schedule that works for you. If you can’t sleep after exercise in the morning, try shifting your workouts later. If you can’t sleep after exercising at night, it might help to schedule your workouts earlier in the day.
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