By Tom DiChiara
The Rumor: Exercising at night can interfere with a good night's sleep
Maybe you're the kind of person who likes to lift weights while watching Late Night With Jimmy Fallon, go running in the park at 10 p.m. or practice Pilates after you've digested your dinner. If so, you've no doubt heard the rumblings that exercising at night is baaaaad for your sleep. After all, exercising raises your core body temperature, increases your heart rate and prompts your system to release stimulating epinephrine (adrenaline). While those are normally desirable outcomes (they're kind of the reason you work out in the first place), popular wisdom says that at night, the effects of physical exertion can keep you up hooting with the owls. The question is: Is this true, or is it just a myth invented by people who are looking for an excuse to bail on their after-work workout?
The Verdict: For the most part, exercising at any time of day will help you sleep
There is anecdotal evidence that some people have difficulty falling asleep after vigorous bouts of late-night exercise -- and Stuart Quan, MD, the Gerald E. McGinnis professor of sleep medicine at Harvard Medical School and editor-in-chief of UnderstandingSleep.org, acknowledges that these individuals should be wary of working out too close to bedtime. "Their adrenaline is high, their brain is active, and it's difficult to wind down," he says. If you fall into that group and have experienced trouble sleeping after a midnight-hour cardio workout or yoga session, Quan recommends that you give yourself a few hours between workout time and sleepy time. This strategy will allow your body temperature to return to its usual 98.6 degrees, your heartbeat to return to its resting rate and your adrenaline levels to stabilize so you can get your Z's.
For most people, however, exercising close to bedtime doesn't appear to adversely affect sleep quality in the slightest. A 2011 study determined that subjects slept just as well on nights when they exercised for 35 minutes right before bed as they did on nights when they didn't exercise.
And the National Sleep Foundation's 2013 "Sleep in America" poll, which studied the sleep habits of 1,000 participants, found that an overwhelming majority (83 percent!) of people who exercised at any time of day (yep, including late at night) reported sleeping better than those who didn't exercise at all. More than 50 percent of vigorous and moderate exercisers slept better on days when they worked out than they did on days when they skipped exercise completely. And only three percent of late-day exercisers said they slept worse on days when they exercised, compared to days when they didn't.
So if right before bed is the only time when you can squeeze in a workout, do it! Not everyone is a morning go-getter who likes to sprint through the pre-dawn streets, Rocky-style. And even fewer have jobs where lunchtime trips to the gym are feasible (though that would be nice). Getting exercise is almost always better than getting no exercise at all. If nothing else, that's definitely an idea worth sleeping on.