Plenty of research suggests that engaging in regular physical activity during the day can help improve sleep at night. Most studies, however, have involved college students or adults with either specific health problems or clinical sleep problems, such as insomnia. Few studies have examined how physical activity influences the quality of sleep of healthy adults.
A study published recently in the journal Sleep Health, is helping to fill that research gap. In the study, researchers at Brandeis University found that when healthy adults — individuals without any symptoms of a clinical sleep problem — increase the time they spend walking each day, they sleep better at night.
The study’s results are encouraging, say its authors, for they suggest that we don’t have to engage in a structured, high-intensity exercise program to improve our sleep. Simply taking more steps during the day — perhaps adding a 20-minute stroll to a lunch break at work or walking the dog for an extra block or two at night — may be enough to help us sleep more soundly.
A public health problem
As background information in the study points out, getting good-quality sleep — or, rather, not getting it — is a huge public health problem in the United States. Lack of sleep has been linked to an increased risk of several chronic diseases, including type 2 diabetes, heart disease and depression. It’s also a major contributor to traffic accidents, industrial accidents and medical errors.
Within any 24-hour period, a third of American adults report not having slept for the recommended minimum of seven hours, and between 50 and 70 million Americans have a sleep disorder severe enough to affect their ability to function during the day.
Nine million Americans over the age of 30 take some kind of prescription or over-the-counter sleep aid to help them fall asleep each night, despite the risk of those products leading to dependence and other negative health effects. Middle-aged and older adults are the most common users of such aids, most likely because of the changes in sleep patterns — most notably, difficulty falling and staying asleep — that often occur with aging.
Researchers have been trying to identify non-drug alternatives for improving sleep. Physical activity has been found to be one of the most promising.
For the current study, the Brandeis researchers recruited 59 middle-aged or older adults (average age: 49) from the greater Boston area. All had full-time jobs and reported sleeping for at least seven hours on most nights. They were healthy enough to walk briskly, although at the start of the study each self-reported walking less than 60 minutes per day.
The participants were given a portable activity monitor, which they were asked to wear for four weeks to track their daily steps and the number of minutes they spent moving. They were then randomly divided into two groups. Those in the intervention group were instructed to increase their baseline number of daily steps in 2,000 increments during each of the four weeks of the study. (For the average person, 2,000 steps is the equivalent of about one mile.) To help them meet that goal, they were given materials about where, when and how they could increase their walking.
The people in the control group received no such instructions.
Each evening during the study, both groups received an email with a link to a survey that asked them questions about their previous night’s sleep, including how long they had slept (when they had gone to bed and when they awoke) and the quality of their sleep.
The study found that walking was positively associated with improved sleep. The participants who averaged the most steps during the month-long study — and who spent the most minutes being active — reported significantly better sleep, on average, than those who walked the least.
That finding was especially true for women.
The improvement was in quality of sleep, not in sleep duration, although that was probably because the study’s participants were already getting the minimum seven hours of recommended sleep.
The effect on sleep appeared to be immediate. Participants — even those who were the least active — reported sleeping better on the nights that followed a day of walking more than was typical for them.
“The fact that both between- and within-person analyses were significant suggests that average patterns of and daily fluctuations in [physical activity] affect sleep,” the study’s conclude.
Limitations and implications
This was an observational study, which means it can’t prove that the increased walking was what caused the improved sleep. In addition, the study was small and relatively short. It also relied on the participants self-reporting how well they slept — not exactly an objective measurement of sleep quality.
Still, these findings are promising.
“The results extend our knowledge by suggesting that metrics such as step counts and daily active time can predict sleep quality and sometimes duration in a healthy population of middle-aged and older adults,” the study’s authors write.
“Recommendations for increasing daily steps could be a feasible way to improve sleep as most Americans have a fitness tracker or smartphone with the capability of measuring steps,” they add.
FMI: You’ll find an abstract of the study on Sleep Health’s website, but the full study is behind a paywall.