Solution for better sleep: exercise, at any time of day

By Deborah Kotz, Globe Staff

I usually find the time to exercise late in the evening, but I often worry that it will interfere with my sleep if I, say, can’t get to a workout until 10 p.m. Sleep experts I’ve interviewed in the past have often recommended against intense physical activity close to bedtime, saying it could interfere with sleep. That’s because “excitement” hormones such as adrenaline, which rise during exercise to give us energy, take about three hours to fall back to normal levels.

Interestingly, studies haven’t shown this to be the case, finding that it didn’t matter whether people worked out in the morning or within 30 minutes of bedtime in terms of the quality and quantity of their sleep.

That research has been backed up by a survey released today by the National Sleep Foundation, which makes the case for exercising to improve sleep -- at any time of the day or night. The survey of 1,000 adults between the ages of 23 and 60 found that vigorous exercisers (running, biking, swimming) were almost twice as likely as sedentary people to report that they had a good night sleep every night or almost every night during the previous week. It didn’t matter whether the survey respondents exercised close to bedtime or first thing in the morning.

On the flip side, one-half of those who didn’t exercise reported waking up during the night on a regular basis and nearly one-fourth had difficulty falling asleep every night or almost every night.

“This finding contradicts long-standing ‘sleep hygiene’ tips that advise everyone not to exercise close to bedtime,” according to a statement on the sleep foundation’s website. “The National Sleep Foundation has amended its sleep recommendations for ‘normal’ sleepers to encourage exercise without any caveat to time of day as long as it’s not at the expense of sleep.”

Those who are being treated for chronic insomnia, however, should continue to restrict late evening and night exercise, the group recommended, if this is part of their treatment regimen.

Deborah Kotz can be reached at dkotz@globe.com. Follow her on Twitter @debkotz2.