Exercizzz: what's the link between sleep and exercise?
Exercise and sleep are essential for a healthy, happy body - and it turns out, more time spent sweating can actually boost the quality of your shut-eye. But just how does moving more lead to better zzz’s, and how can you maximise these body benefits?
We asked experts in sleep, exercise, and neurology for the science behind exercise and how it makes you sleep better. Here's what they had to say:
Exercise can reduce cortisol levels and risk of weight gain
“Lack of sleep, and dysfunctional sleeping can create domino effects of at least ten different mechanisms falling out of sync, many of which affect weight loss,” says W. Christopher Winter, M.D., president of Charlottesville Neurology and Sleep Medicine and author of The Sleep Solution.
First, the stress hormone cortisol will ramp up, which can keep you awake at night and affect glucose metabolism (the way you store fat). Also, when you sleep less, you tend to eat more because leptin, the hormone that signals ‘I’m full and satisfied’ gets suppressed,” Winter says. To add to the triple threat, ghrelin - the hunger hormone that is made in the gut - also increases when you don’t sleep well, making you crave carbs, he explains.
Exercise halts the first of those chain reactions by reducing cortisol levels, says Meg Furstoss, MS, CSCS, founder of Precision Sports Performance. “Most people start to feel the impact of the day’s stress at night, so exercise helps clear that out.”
Exercise can help you fall asleep faster
Furstoss recommends doing cardio-based exercises, which have been shown to reduce the signs of insomnia in healthy people, according to the journal Sleep. But she also strongly recommends incorporating resistance training for sleep and fat loss goals. “Weight lifting is best for weight loss because lean muscles burn fat at a quicker rate,” she says.
Research shows that resistance exercise such as weight lifting alone (i.e., when not done at the same time as cardiovascular exercise) is super beneficial for all aspects of sleep, according to 2017 study analyses in Sleep Medicine Reviews. Resistance training was shown to raise the quality of sleep and to improve anxiety and depression. Study analyses of more than 3,000 adults from age 18 to 85 found that exercise also aided in falling asleep faster and reducing the chances of feeling overly sleepy during the day, according to the report published in Mental Health and Physical Activity.
Vigorous activity can help you sleep more deeply
Slow-wave sleep is where a lot of the restorative magic happens, and exercise can help you get more of it. Your muscles, bones, and tissues can be repaired during non-REM (rapid eye movement), slow-wave sleep. Once that sleep becomes REM (aka the dream state), the parts of your brain used for learning get stimulated.
Researchers from the University Of Basel in Switzerland objectively monitored the sleep of more than 40 students to test whether vigorous physical activity (20–60 minutes) created better sleep outcomes than moderate exercise. Those who did vigorous activity slept longer overall, spent more time in stage 4 (deep) and REM (rapid eye movement) sleep, and had less light sleep in exchange for more slow-wave sleep.
Morning exercise may help improve your sleep
The key: aim to be consistent, Winter says. “Morning exercise is a very good thing - maybe one of the best things - to do for our sleep. Pair your workout with light, like the sunrise, starting every day at the same time and with a bit of food,” he adds. “The habit provides your brain a strong cue to suppress melatonin - the hormone that helps you fall asleep, and then it surges the feel-good hormones dopamine and serotonin,” Winter says, which can also help reverse depression and boost your mood overall.
There’s no magic formula in regards to what types of exercise create optimal sleep, or when you should do it. Most recommendations advise a few hours gap between working out and bedtime, to allow body temperature, heart rate, and adrenaline levels to all return to normal after exercising. By contrast, a study published in Sleep Medicine found that young adults who engaged in intense physical activity 90 minutes before bed were more likely to report that they slept better, including more deep sleep and shorter sleep onset times. But that timing’s not right for everyone, so you’ll have to experiment.
“All exercise helps with sleep, be it low to moderate to high intensity,” says Pradeep Sahota, MD, Director of Sleep Disorders Center at University of Missouri School of Medicine. “It’s better to match it to one’s general physical health, fitness, and work schedule. It can vary from breathing exercises, tai chi, or yoga to brisk walking, biking, or higher intensity workouts. You’ll get the best results if you exercise in the morning or at least four hours before bedtime, and if done outdoors, there are additional benefits of light exposure,” Sahota says.