For many people, fitting exercise in during the day can be tough—leaving mornings or evenings as the only option. But is one better for sleep and energy levels? Experts weigh in.
Morning exercise is generally thought to support one important aspect of good sleep: drifting off faster, according to sleep neuroscientist Arsenio Paez, PhD, executive director of the Canadian Sleep Society.
Morning workouts—especially if done outdoors—may help to stimulate the release of the hormone melatonin, which regulates the body’s internal clock by signaling it’s time to wind down when it gets dark.
Not only can falling asleep faster lead to more overall rest (and, by extension, better energy levels), but exercise in general helps increase energy in several ways, including increasing blood flow and promoting mitochondrial activity in muscle cells. Plus, exercise releases endorphins that could give you a natural mental boost to start the day.
It’s worth noting, however, that waking up too early to squeeze in a workout could backfire, especially if it cuts into your sleep and you’re not able to make up those lost hours at night, Scott Kutscher, MD, a professor of sleep medicine at Stanford University, told Health.
And while morning exercise may help you fall asleep more easily, that doesn’t necessarily mean you’ll sleep better overall: Research is mixed on whether morning activity improves sleep quality or total sleep time.
Gentle evening workouts have their perks, too, said Mark Riederer, MD, an associate professor of orthopedics and sports medicine specialist at the University of Utah.
Light exercise at night may help ease pent-up stress or anxiety, creating a “state of calmness right before bed,” he told Health. It might also help you sleep more soundly by reducing how often you wake up during the night, Paez added.
But vigorous workouts too close to bedtime—specifically, within an hour—are “probably not the best,” Riederer noted. Intense exercise can raise the body’s core temperature and stimulate the nervous system, making it harder to relax.
Whether strenuous evening workouts disrupt overall sleep, however, is still up for debate: Some studies suggest they not only do not interfere with rest, but may improve subjective sleep quality or increase total sleep duration.
Of course, if an evening workout cuts into your nightly shuteye, you may feel drained the next day. But the good news is, as mentioned earlier, exercising itself kicks off a chain of biological effects that can help boost your energy over time.
How working out in the morning or evening affects sleep and energy depends on the type of workout, your typical sleeping and eating patterns, and other individual factors. There’s also limited research directly comparing the two.
In studies that do examine how exercise timing affects sleep specifically, the differences appear to be minimal. “There aren’t major statistical differences in [sleep] quality between exercise in the morning and exercise in the evening,” Kutscher said.
Still, Paez said it could be helpful to first consider your specific sleep challenges when deciding when to exercise: If you have trouble falling asleep, a morning workout may help you drift off faster. But if you tend to wake up during the night, a light evening workout could help you stay asleep longer.
Vigorous evening exercise, on the other hand, could keep you up if done too close to bedtime.
Ultimately, experts said the most crucial factor—for sleep, energy, and the overall benefits of exercise—isn’t when you exercise, but that you do it consistently.
“The most important thing is trying to get those 150 minutes of moderate intensity exercise throughout the week, as recommended for all Americans for a healthy lifestyle,” Riederer said.
