Easy-to-Moderate Exercise Before Bedtime Promotes Deep Sleep

Squeezing a workout into the daytime hours of a jam-packed weekly schedule often takes Herculean effort or is downright impossible for many people. Unfortunately, some sleep experts offer a blanket recommendation to "avoid evening exercise" without fine-tuning their prescriptive advice based on the impact various intensities of physical activity have on sleep quality and insomnia. Prohibiting evening exercise across-the-board creates a conundrum for anyone who wants to sit less and move more but doesn't have time during the day to work out.

Fortunately, for anybody whose daytime schedule is too hectic to accommodate a healthy dose of physical activity, there is good news. A recent paper, "Effects of Evening Exercise on Sleep in Healthy Participants: A Systematic Review and Meta-Analysis," offers fresh, evidence-based advice on the do's and don'ts of exercising before bedtime. Contrary to popular misconceptions, the researchers conclude that non-vigorous exercise before bedtime tends to improve sleep quality.

For this meta-analysis, researchers from the Institute of Human Movement Sciences and Sport at ETH Zurich analyzed 23 studies related to the evening exercise-sleep connection. As mentioned earlier, the researchers found that easy-to-moderate exercise in the four hours before bedtime does not lower sleep efficiency.

In fact, the meta-analysis shows that when a study participant had done some non-vigorous exercise before bedtime, he or she spent more time in deep sleep. Compared to participants in non-exercise control groups, those who participated in easy-to-moderate physical activity before bedtime significantly increased rapid eye movement latency and slow-wave sleep.

Moderate intensity exercise shortly before bedtime does not negatively affect sleep. At most, vigorous exercise close to bedtime might have a negative effect. Each symbol in this overview represents one set of experimental data.

Source: ETH Zurich/Jan Stutz

As you can see in the upper-right red zone of the diagram above, vigorous physical activity within one hour of bedtime is the only type of evening exercise that appears to have a detrimental impact on sleep.

"As a rule of thumb, vigorous training is defined as training in which a person is unable to talk. Moderate training is physical activity of an intensity high enough that a person would no longer be able to sing, but they could speak," Christina Spengler, head of the Exercise Physiology Lab at ETH Zurich, said in a statement. "It is well known that doing exercise during the day improves sleep quality. Now we have shown that, at the very least, exercising in the evening doesn't have a negative effect."

The authors sum up their meta-analysis: "Overall, the studies reviewed here do not support the hypothesis that evening exercise negatively affects sleep, in fact, rather the opposite. However, sleep-onset latency, total sleep time, and sleep efficiency might be impaired after vigorous exercise ending one hour before bedtime."

"The data shows that moderate exercise in the evening is no problem at all," Jan Stutz, a doctoral student in Spengler's research group and lead author of this meta-analysis said. But again, Stutz emphasizes: "Vigorous training or competitions should be scheduled earlier in the day, if possible."

The bottom line: Spengler and Stutz recommend trusting the evidence-based findings of their meta-analyses, but also recommend using common sense and listening to your body. Everyone reacts differently to exercise. If for some reason, you find that any intensity of evening exercise seems to disrupt your sleep, try working out at least four hours before bedtime.