Young adults who exercised vigorously before bed ended up getting better sleep than their peers who reported less strenuous evening activity, a new study found.
The results, based on sleep patterns during a single night, go against the usual advice to avoid being too active before bed.
"We believe that the present study has the potential to shed light on the issue of whether evening exercising should be discouraged," Serge Brand of the University of Basel in Switzerland and his colleagues write.
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"The findings may also have practical implications, since, for most employed adults and parents, evening hours often provide the only opportunity for exercise," the researchers add.
They studied 52 Swiss high school students who were an average of 19-years-old and played sports two or three times per week.
The participants followed their normal routine on the day and night of the study, including playing sports for 65 to 90 minutes in the evening and ending about one and a half hours before their usual bedtime.
Before going to bed, students rated their mood and hunger levels and filled out a questionnaire that was designed to evaluate how vigorously they had exercised. That night they used a device that measures sleep patterns, called a sleep-EEG.
Brand's team found that students who reported more exertion during sports fell asleep faster, woke up fewer times during the night and slept more deeply than those who had exercised less vigorously.
Higher levels of exertion were also linked to increased tiredness, better mood and less hunger at night. The same was true when students repeated those ratings the next morning, according to findings published in Sleep Medicine.
The results jibe with another recent study that found people who exercised in the evening reported sleeping just as well as those who didn't.
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Dr. Phyllis Zee, who studies sleep patterns at Northwestern University Feinberg School of Medicine in Chicago, called the new findings "interesting."
"As (the researchers) pointed out there have been other studies to show that exercising in the evening - perhaps not as close to bedtime as in this study - was not detrimental to sleep," she told Reuters Health.
"One of the reasons why sleep is deeper, at least acutely, after more vigorous exercise is that sleep is also for energy balance and metabolism," she said. "And therefore what you've done is increase your metabolic need for sleep."
Zee said the current study had some limitations, which were acknowledged by the authors.
For instance, the study only enrolled young, healthy adults, so it's not clear that the results would be the same for older adults.
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"This is a very specific group," Zee said. "This group in general does not tend to suffer from insomnia as much - that tends to be in the older groups."
She added that because the study only covered one night of exercise and sleep, the findings might look different over time.
"I would imagine that if you did that every night that you're more likely to actually delay your sleep time a little bit," she said.
Still, Zee said it's better to exercise at night than to not exercise at all, especially for people who don't have sleep problems.
"People who do have trouble falling sleep should still be cautious about exercising too close to bedtime," she said, as getting the body and brain going could make it more difficult to get to sleep.
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