Working Out This Many Hours Before Bed Will Negatively Impact Your Sleep

They determined that overall, exercising at night did not disrupt nighttime sleep in most people—with one caveat. “When exercise ended less than two hours before bedtime, sleep was negatively impacted,” Frimpong said in a news release. “It took longer for participants to fall asleep and sleep duration decreased.”

Exercise that was completed two to four hours before bed did not disrupt sleep in the same way. In fact, Frimpong explained, “Our analysis showed that when exercise ended two hours before bedtime, there were sleep benefits, including the promotion of sleep onset and increased sleep duration.” Although, interestingly enough, those who exercised two to four hours before bed spent less time in the REM sleep stage—where most dreaming occurs—compared to a no-exercise control.

Overall, the research concludes, exercising in the early evening, two to four hours before bed, seems to help sleep, not harm it—especially for those who spend most of the day sedentary. In the studies examined, cycling was the exercise that best supported deep sleep, and night owls tended to benefit from evening exercise more than early birds.