April 3, 2024 – Perhaps there is nothing that eludes more people in the world more than sleep. Sleep deficits cross borders and traverse seas, affecting millions across the globe.
In the United States, roughly 1 in 4 adults have insomnia every year, but fortunately, 75% are able to recover what are considered normal sleep patterns: falling asleep easily, staying asleep without waking during the night or too early in the morning, and feeling refreshed the next day.
An important solution to overcoming sleep deficits might be staying active. Though sleep experts have long touted the benefits of regular exercise as an important part of behavioral therapy for treating insomnia, one thing in particular might make it work: consistency.
“It turns out that staying physically active can significantly reduce the risk of experiencing insomnia symptoms and extreme sleep durations,” said Erla Björnsdóttir PhD, a clinical psychologist and researcher at Iceland’s University of Reykjavik. She is lead author of a new study that investigated the relationship between physical activity and insomnia symptoms in over 4,000 European adults (ages 39 to 67 years) in nine countries.
People in the study were required to answer questions on the frequency and duration of physical activity at the start of the study, and 10 years later, on physical activity, insomnia symptoms, sleep duration, and daytime sleepiness. These metrics were captured in the European Community Respiratory Health Surveys II and III, and sleep-related symptoms were measured using validated instruments.
Over a 10-year follow-up period, 25% of those studied reported that they were persistently active (in other words, they exercised at least two to three times a week for at least 1 hour or longer per week). These people were 42% less likely to find it difficult to fall asleep, had a 22% lower odds of having any insomnia symptoms, and they were also 55% more likely to clock normal sleep (defined as 6 to 9 hours a night).
They were also less likely to report sleeping extremes – that is, short (6 hours or less) or long (9 hours or more) sleep – both of which have been linked to daytime sleepiness. What’s more, almost 21% of the people who became active during the study were also likely to become normal sleepers.
“These findings remained significant even after adjusting for factors like age, gender, smoking, and body mass index,” said Björnsdóttir.
Sleep Patterns, Circadian Rhythms
Björnsdóttir noted that the study didn't account for certain things, such as having other medical conditions alongside sleep issues, being older than 67, and declining mobility. These things could affect sleep patterns and overall health outcomes, she said.
“There may be diminishing returns as individuals age and experience age-related changes in activity levels over time,” she said, “but research suggests that regular exercise can still confer numerous benefits (such as improved sleep quality, cognitive function, and overall well-being) in elderly individuals who’ve been consistently active,” she said.
Although it remains unclear if timing of activities or certain types of activities yield better results, a recent analysis suggested that heavy exercise at night has a negative effect on sleep quality and that exercising during the morning and afternoon might work better in terms of sleep regulation.
The reason? “Zeitgeber.”
“’Zeitgeber’ is a German term for external cues that help us know when to do things, our circadian rhythm,” said David Kuhlmann MD, a sleep specialist and medical director of sleep medicine at Bothwell Regional Health Center in Sedalia, MO. For people with insomnia, these include having a regular sleep schedule, avoiding the bedroom except for sleep and sex, a darkened room, limited alcohol and caffeine before bedtime, creating a comfortable sleep environment, avoiding napping during the day, and regular exercise.
“In general, I recommend morning exercise for people who are trying to fall asleep faster in the evening versus closer to bedtime to avoid moving or delaying their circadian rhythm,” he said. Data has shown that physical activity within an hour of bedtime interrupts the ability to fall asleep (sleep latency), total time asleep, and the ratio between time asleep and time spent in bed (also known as sleep efficiency). This is especially true of aerobic exercise, which releases endorphins that prevent the brain from calming down.
Kuhlmann also pointed to the role that body temperature plays. “The higher you get your body temperature up during the day, the lower the body temperature gets at night, and the more slow wave sleep (i.e. deep sleep) you achieve,” he said. Conversely, raising the body temperature at night, such as through vigorous exercise, sends a signal to the body clock that it’s time to be awake. It takes 30 to 60 minutes for core body temperature to fall and promote sleepiness.
Insomnia-Activity Connection Not a One-Size-Fits-All Proposition
What happens if you are an exercise junkie and you still can’t sleep? Danielle Ricks, director of education and community engagement for Montgomery County Media in Silver Spring, MD, and an adjunct professor at Howard University in Washington, DC, is one of those junkies and said that for her, sleep is elusive.
Ricks shared that her insomnia started after a bout of full-blown Crohn’s disease and several courses of prednisone.
“Although I’ve been off the medication for 2 decades now, I’ve never gotten my sleep patterns back properly. I don’t have trouble falling asleep, but I have trouble staying asleep despite having been consistently exercising for 30 years,” she said. Ricks does regular weight training and aerobic activity, as well as meditation.
The same rings true for Tracy Endo, a swim instructor and Uber driver based in Virginia. Now 58, Endo said that she started having sleep issues roughly 15 years ago – issues that she said were caused by stress from changing hormones and single parenting. “I’ll wake up at 3:30 in the morning and not be able to go back to sleep, and that happens, on average, three or four times a week,” she said.
As with Ricks, physical activity has been consistent in Endo’s life. “I’m an avid hiker,” she said, noting that she hikes 3 to 4 miles at least four times a week during the winter and much more during the warmer months. Endo also said that she has been an Ironman triathlete and goes out regularly on her standup paddle board, but her sleep patterns have rarely changed.
For every Ricks or Endo, there are people for whom regular physical activity reduces insomnia symptoms. An important thing to keep in mind is that not everyone who wakes during the night or has trouble falling asleep has true insomnia, a key reason why Kuhlmann said that he believed that it was important to set realistic expectations, especially as we grow older.
