Scientists warn exercising before bed could be doing you more harm than good

We all know that getting enough exercise and sleep is vital for our overall well-being, however many of us don’t get enough sleep and conversely do not do enough exercise especially as we lead increasingly sedentary lifestyles.

So it would seem that fitting in your workout at any time is a good thing but scientists are now warning that exercise before bedtime may affect sleep duration, timing and quality, which is concerning as sleep deprivation is linked to higher rates of heart disease, depression and an increased risk of dementia.

For the first time, scientists from Monash University (MU) and Swoop (a wearable tech company), have identified that exercising four hours or less before bedtime was linked to falling asleep later, getting less and worse quality sleep which can lead to a higher resting heart rate and lower heart rate variability in people.

The study’s first lead author and MU academic, Dr Josh Leota said the researchers wanted to understand “the important yet puzzling” link between the timing of exercise and sleep.

“Intense exercise in the evening can keep the body in a heightened state of alertness, which is why public health guidelines have previously advised against working out too close to bedtime. However, findings from controlled laboratory studies are less conclusive, with many suggesting that evening exercise doesn’t necessarily disrupt sleep,” he said.

“These studies have relied on small sample sizes and laboratory settings, and rarely involved exercise bouts that elicit substantial cardiometabolic demand on the body, calling into question the external validity of such findings.”

In the study, the research team wanted to examine the relationships between evening exercise, exercise strain, sleep and nocturnal cardiac activity, so monitored almost 14,700 participants from multiple countries who wore a multi-sensor biometric device (WHOOP Strap) to record exercise, sleep and cardiovascular data.

Over 12 months, four million nights of data were gathered from the participants who engaged in high strain exercise routines such as HIIT workouts (high-intensity interval training), football and rugby games or a long run –  activities that lead to sustained increases in breathing, heart rate, core body temperature and mental alertness.

Dr Leota said the findings suggested that people may benefit from concluding exercise at least four hours before their bedtime if they want to improve sleep health.

“If exercising within a four-hour window of bedtime, people could choose brief low intensity exercises, such as a light jog or swim, to minimise sleep disruption and allow the body to wind down,” he said.

In addition, Monash University’s Dr Elise Facer-Childs said the results showed a clear and consistent relationship across all factors in the study.

“Evening exercise—particularly involving high levels of cardiovascular strain—may disrupt subsequent sleep, resting heart rate, and heart rate variability, thereby impairing a critical stage of the recovery process,” she said.

“Our novel and timely findings have significant implications for public health messaging around timing, duration and intensity of exercise and present a critical step towards improving population sleep health—an issue of central importance given two in three Australian adults report at least one sleep problem and one in five adults fail to achieve the recommended seven or more hours of sleep per night.”

So for all you gym junkies out there, now’s the time to reset your fitness timetable but if you still struggle to reach 40 winks, there are often underlying causes.

Sleep Expert Carmel Harrington, who has a PhD in Sleep Medicine explains that “from around the age of 20, deep sleep decreases continuously and in old age makes up only about 10 per cent of our total sleep time.”

If you are finding it difficult to get a proper night’s sleep each night there are a number of supposed remedies to help someone fall asleep faster and deeper, but if counting sheep isn’t doing the trick then Harrington suggests some enjoyable and “mentally stimulating” activities to help you drift off come bedtime.

“A great thing to take up is dancing – it is a physical and mental challenge and is lots of fun! And having fun is important when it comes to sleep,” she said.

“It’s important as we age, to continue to exercise regularly and refrain from sleeping during the day. A 20-minute nap is ok, but definitely no longer.”

DO NOT:

• Sleep in for more than an hour past your regular wake-up time on the weekends
• Have caffeine after midday
• Drink alcohol – more than one glass a day will affect your sleep quality
• Sleep during the day (a nap of 20 minutes is ok)

IMPORTANT LEGAL INFO This article is of a general nature and FYI only, because it doesn’t take into account your personal health requirements or existing medical conditions. That means it’s not personalised health advice and shouldn’t be relied upon as if it is. Before making a health-related decision, you should work out if the info is appropriate for your situation and get professional medical advice.