A recent study suggests that going to bed earlier may lead to more physical activity the next day—even if you sleep the same amount of time as usual.
The study, published in the Proceedings of the National Academy of Sciences in June, also revealed a surprising link between getting more shut-eye than normal and lower activity levels the following day.
While it’s known that both sleep and physical activity affect health, past research hasn’t clearly shown how the two interact on a day-to-day basis, said Josh Leota, PhD, study co-author and a research fellow in the School of Psychological Sciences at Monash University.
“We wanted to cut through the noise and understand how average sleep and nightly changes in sleep are linked to physical activity the next day in real-life settings,” Leota told Health.
For the study, researchers analyzed a year’s worth of sleep and movement habits of 20,000 physically active adults who wore an activity tracker called WHOOP.
After analysis, the team discovered that:
- Earlier bedtimes were linked to more physical activity the next day. Those who went to bed around 9 p.m. clocked about 15 more minutes of moderate to vigorous activity compared to those who turned in at 11 p.m. (the average bedtime) and 30 more minutes than those with 1 a.m. bedtimes. Going to bed earlier than usual also boosted next-day activity. The biggest gains were seen when participants went to bed 1.5 to 3 hours earlier than their normal time—without changing the duration of their sleep.
- Less sleep led to more physical activity the next day. Interestingly, participants who averaged fewer than seven hours of sleep logged 17 to 30 additional minutes of general movement and 10 to 31 more minutes of moderate to vigorous activity compared to those who averaged seven hours of sleep. In contrast, getting more than seven hours—or more sleep than usual—was linked to lower physical activity levels the following day.
The results were validated by a secondary study using FitBit data from 6,000 participants in the All of Us Research Program, a large-scale study led by the NIH designed to collect health data that reflects the diversity of United States residents.
That secondary study offset any bias that could have crept into the first one, given that WHOOP users are known to be highly health conscious, said Christopher E. Kline, PhD, FACSM, FAHA, an associate professor at the University of Pittsburgh’s Department of Health and Human Development who focuses on the relationships between physical activity, sleep, and cardiometabolic risk.
“The fact that the ‘All of Us’ results were similar though smaller in magnitude to the WHOOP results really reinforces the overall findings,” said Kline.
Kline found the link between sleep-onset timing and next-day moderate to vigorous activity especially notable. Most research exploring that connection has been limited by reliance on self-reported data or controlled lab settings, Leota said.
The study’s main findings—that going to bed earlier and sleeping less may lead to more physical activity the next day—might be explained by a straightforward factor, Leota explained: both behaviors can create more time to move.
“Going to bed earlier may mean waking up earlier, giving people more time and energy to exercise before work or daily responsibilities,” he said. “On the other hand, sleeping longer might squeeze out time for physical activity, especially in busy schedules.”
Though the new study suggests that sleeping fewer than seven hours may lead to more physical activity the next day, the Centers for Disease Control and Prevention recommends that adults get at least that amount of sleep. Instead of regularly cutting back on sleep just to fit in more movement, the study authors recommend focusing on shifting your bedtime earlier.
To help with that transition, your best bet is to move your bedtime gradually, advised Kline. He recommends:
- Minimizing bright light exposure in the evening
- Prioritizing bright light—especially alongside exercise—when you wake up
If, despite your best efforts, you’re still a night owl, Leota suggests trying to incorporate more activity into your day.
One way to ensure that you get more exercise is to simply schedule it in, advised Kline. “It doesn’t have to be morning exercise,” he said. “But whatever time you choose to perform it, make sure it is a protected time during the day that doesn’t get swallowed up by responsibilities or tasks that run over in time or emerge during the day.”
