Here’s another excuse you need to chalk off.

No excuse!

A widely held belief among many people (and even some scientists) is that if you want to sleep well at night, you shouldn’t work out in the evening. Since most people work day hours and few are willing to wake up at 6-ish to start their day with a workout, this can be quite troublesome. But according to a new review of 23 studies, you shouldn’t worry. You can work out any time you want, and you’ll sleep just fine — maybe even better.

Researchers from the Institute of Human Movement Sciences and Sport at ETH Zurich combed through the literature and found 23 studies that meet their quality requirements. They found no reason to believe that afternoon physical activity interferes with the quality of sleep. If anything, they found that participants report a very slight improvement.

“If doing sport in the evening has any effect on sleep quality at all, it’s rather a positive effect, albeit only a mild one,” says Christina Spengler, head of the Exercise Physiology Lab at ETH Zurich.

There is, however, one very important exception: vigorous exercise carried within one hour of going to sleep. The reason for this is that the heart doesn’t have enough time to return to its regular resting beat.

Simply put, a mild or moderate workout can be carried out any time, and a vigorous workout can be carried out any time except for right before going to sleep. There is some vagueness and subjectivity around what “moderate” or “vigorous” mean. Researchers clarify:

“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,” Spengler says.

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 here represents one set of experimental data. (Visualisations: ETH Zurich / Jan Stutz).

The bottom line is that you should emphasize working out, and not care so much about the time when you do it. According to official recommendations, healthy adults should do at least 150 minutes of moderate exercise each week. Everyone exercises in his or her own way. Listen to your body, don’t push it too hard — but do work out.

“People can do exercise in the evening without hesitation. The data shows that moderate exercise in the evening is no problem at all,” says Jan Stutz, a doctoral student in Spengler’s research group and lead author of the analysis, which was published in the journal Sports Medicine.

Journal Reference: Stutz J, Eiholzer R, Spengler CM: Effects of Evening Exercise on Sleep in Healthy Participants: A Systematic Review and Meta-Analysis. Sports Medicine, 29. Oktober 2018, doi: 10.1007/s40279-018-1015-0.