Should You Avoid Exercise Before Bed? The Answer May Surprise You
I like to do most of my cross-training at the gym in the evening. Is it affecting my sleep?
While there’s ample research noting that regular exercise can improve sleep quality, as well as lower the risk of sleep disorders, we’re generally discouraged to do intense physical activity too close to bedtime, because your body doesn’t have enough time to wind down.
However, a new study in BMJ Open Sport & Exercise Medicine suggests “mini-bursts” of exercise that break up evening sedentary time can actually be a boon for sleep.
Researchers asked 28 men and women to do two different evening activity sessions. In one, participants sat continuously for a four-hour period while watching shows on a streaming service – similar to what many people do most nights, says the lead researcher, Professor Jennifer Gale from the University of Otago in New Zealand.
In the other session, participants still watched shows, but they broke up that four-hour block every 30 minutes with three bodyweight exercises – calf raises, squats and alternating knee raises – for three minutes per session. Each exercise was performed for 20 seconds and three rounds each.
“Although we used specific exercises, people could probably get a similar benefit from other types of activity, such as marching in place or walking up and down stairs in their house,” Gale says.
Participants then provided information on sleep factors – such as the ability to fall asleep quickly, waking up throughout the night, and overall sleep duration – after both the sedentary and the active sessions. Sleep was also measured using a wrist monitor.
Sleep disruption frequency was the same on both nights (sedentary and active); but during the night after the activity breaks, participants slept almost 30 minutes longer. Gale said that researchers were surprised by the results, as they expected that the short activity bursts would actually diminish sleep quality.
“We were happy to see that wasn’t the case,” she says. “The activity breaks actually extended sleep duration without affecting sleep quality. That was very exciting.” But she noted that the mechanism is unclear, and more research will need to be done around why these mini-bursts might help with sleep.
One potential reason is that short bouts of activity can help regulate blood sugar in the evening. Previous research has linked sleep issues and blood sugar problems, to the degree that several studies have suggested that short sleep duration or insomnia can raise the risk of developing type 2 diabetes.
Another avenue for research is looking at the effects of short evening activity bursts, combined with longer, more intense sessions done earlier in the day. For example, a study in Sleep Medicine on people with insomnia found that morning exercise reduced sleep disruption later that night.
In short, to answer the question: don’t do your cross-training too close to bedtime; rather give your body a few hours to wind down before sleep. But don’t be afraid of some minor exercise closer to bedtime, as this might actually improve the quality of your sleep.