Does exercising before bed take a negative toll on sleep quality?

For many, waking up at the crack of dawn and heading to the gym for an early morning workout is a sure way to start the day right. After all, it’s the “early bird” that gets the worm, right?

Not if you’re a night owl like me. If it weren’t for 24-hour gyms, I would never have set foot on a treadmill – and I know I’m not alone.

That’s why it can be frustrating that working out late at night tends to get such a bad rap. Common wisdom suggests that the combined effects of exercise – including an increased heart rate, higher body temperature and a boost in adrenaline and cortisol levels – are a recipe for disaster when it comes to getting a good night’s sleep.

But what about those of us who work odd hours and can only keep a late gym date – or those who, like me, simply prefer to live – and exercise – by night?

Better late than never

As it turns out, the effects of working out before bedtime aren’t quite as cut and dried as some might think. Dr Stuart Quan, a professor of sleep medicine at Harvard Medical School and editor of UnderstandingSleep.org, says the best workout time generally varies from person to person.

“There may be some people who won’t have any problems,” says Dr Quan. “However, if the person already has trouble going to sleep, exercise in close proximity to bedtime may worsen the problem.”

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Dr Quan says that while working out can make you feel physically tired, “mentally, you may be revved up. In addition, there may be higher amounts of cortisol or adrenaline in your body which may inhibit sleep.”

However, the sleep expert says both cortisol, a steroid hormone, and adrenaline, which increases blood flow to muscles, sugar levels and output of the heart, only take roughly an hour to regulate and get back to normal.

A 2013 study carried out by the National Sleep Foundation found that “while some believe exercising near bedtime can adversely affect sleep and sleep quality”, no major differences were seen in sleep quality between those who had performed “vigorous and/or moderate” exercises within four hours before bedtime.

The study, which included 1,000 participants from the United States, found that 17 per cent of people who exercised within four hours before bed enjoyed “very good overall sleep quality”, with 59 per cent having a “fairly good” night’s rest. Meanwhile, 22 per cent of people who exercised more than four hours before bed had “very good” sleep quality, with 58 per cent experiencing a “fairly good” rest.

Overall, the study found that 83 per cent of “vigorous exercisers” reported very or fairly good sleep quality, regardless of the time of day they chose to work out, compared to 56 per cent of non-exercisers.

Time to unwind

The National Sleep Foundation compares working out at night to taking a warm bath. “Just like your body cools off post-bath, making you feel sleepy, a post-workout cooling may also help to set the stage for sleep.” All in all, the sleep foundation suggests experimenting with working out at different times of the day to see what works best with your individual sleep patterns.

According to Dr Quan, our sleep patterns are largely dictated by genetics. “Morningness and eveningness depends on one’s circadian rhythm,” he says. And one’s circadian rhythm, or natural 24-hour body clock, is largely dictated by genes that are inherited, Dr Quan adds.

“Twin Studies, where identical twins and non-identical twins are studies, suggest that more than 50 per cent of morningness/eveningness is accounted for by inheritance,” says Dr Quan. “The remainder is environmental factors,” such as lifestyle choices and work scheduling.

Dr Quan says those who do prefer to work out late at night should give themselves at least an hour to cool down before going to bed and to “try to get at least seven hours of sleep per night and keep regular hours”. But ultimately, when it comes to night hawks and exercise, the best motto to live by might be “better late than never”.

For information on how to get a good night's rest, visit UnderstandingSleep.org