If you’re hoping to log more exercise tomorrow, the secret might be simpler than you think. Go to bed earlier tonight. A fascinating new study led by researchers at Monash University in Australia has found a significant link between bedtime and physical activity levels the next day. The research doesn’t definitively prove that early bedtimes cause more exercise. However, it uncovers a striking correlation. This finding has powerful implications for personal health and public policy.
The study stands out because of its sheer scale and detail. Researchers analyzed wearable data from 19,963 people over an entire year. They captured nearly six million night-and-day reference points.
The large sample enabled the team to explore sleep patterns in everyday life. They also examined exercise patterns outside controlled lab conditions. The findings were also replicated in a second, independent dataset of 5,898 people, lending additional credibility to the results.
KEY FINDING: EARLY BEDTIMES CORRELATE WITH MORE EXERCISE
Overall, the data showed that earlier bedtimes were linked to significantly higher levels of moderate-to-vigorous physical activity the following day.
Here are some striking examples:
- Participants who went to bed at 9:00 p.m. logged an average of 30 minutes more exercise than those who went to bed at 1:00 a.m.
- Compared to the average bedtime of 11:00 p.m., going to bed at 9:00 p.m. still resulted in 15 extra minutes of exercise.
This suggests that simply shifting bedtime forward could help people fit more movement into their day.
WHY MIGHT EARLY BEDTIMES BOOST EXERCISE?
The researchers propose several explanations for this connection:
- Later bedtimes can lead to poorer sleep quality, making people more tired the next day and less motivated to exercise.
- Staying up late may reflect busier lifestyles or more time spent on screens, which can both crowd out exercise opportunities.
- Going to bed early may help avoid “social jetlag.” This is the conflict between natural sleep rhythms and structured work schedules. This conflict is known to sap daytime energy.
Interestingly, wake-up times were not included in the data. Thus, the study couldn’t directly test whether early risers also woke up earlier. It also couldn’t determine if they had longer days to fit in workouts.
HOW SLEEP DURATION FACTORED IN
Bedtime wasn’t the only variable affecting exercise. The amount of sleep also played a role—though in a somewhat counterintuitive way.
Participants who averaged 5 hours of sleep per night logged 41.5 more minutes of exercise than those who averaged 9 hours of sleep. Yet, researchers caution against interpreting this as evidence that less sleep is better. Chronic sleep deprivation carries serious health risks, including impaired memory, weakened immunity, and higher rates of chronic disease. It’s possible that some highly active people were also simply sleeping less because of busy schedules.
Perhaps most compelling was this finding: when participants went to bed earlier than usual but still got their usual sleep duration, they often logged their highest exercise levels the next day. This suggests that bedtime itself, independent of sleep length, plays an important role.
PUBLIC HEALTH IMPLICATIONS: A NEW APPROACH TO LIFESTYLE PROMOTION
The study’s authors argue that the findings could inform more effective health campaigns. Traditionally, sleep and exercise are promoted as separate behaviors. But this research suggests that targeting bedtime habits could be a simple, actionable way to boost daily activity.
Psychologist Josh Leota, one of the lead researchers, explained: “These insights carry meaningful implications for public health. Health campaigns could encourage earlier bedtimes. This approach would naturally promote more active lifestyles, rather than just promoting sleep and physical activity independently.”
SOCIAL JETLAG: A HIDDEN BARRIER TO MOVEMENT
One concept highlighted in the study is social jetlag. This refers to the mismatch between your biological sleep preferences. An example is being a natural night owl. It also includes your social obligations, such as working 9 to 5.
When people routinely stay up late, they often have to wake early for work. As a result, they can end up in a chronic state of sleep debt. Over time, this can:
- Reduce energy and motivation
- Increase daytime sleepiness
- Interfere with exercise and other healthy behaviors
The researchers believe that early bedtimes may help reduce social jetlag, supporting better rest and more physical activity.
A FEW CAVEATS TO KEEP IN MIND
Despite the promising findings, the study has limitations. Because it is observational, it cannot prove that going to bed early directly causes higher activity levels.
Other factors—like personality traits or work schedules—may also contribute to the association. For example, people who are naturally more organized or health-conscious may both go to bed early and exercise more.
As psychologist Elise Facer-Childs notes: “Our findings are consistent across different populations and show that if you can get to sleep earlier than usual whilst keeping your sleep duration the same, you may be more likely to increase your physical activity the following day.”
Still, she emphasizes the need for controlled trials to better understand cause and effect.
WHAT THIS MEANS FOR YOU
Even with these caveats, the takeaway is encouraging: a small change in bedtime could make a real difference in how active you feel the next day.
If you often struggle to get moving, consider these tips:
- Start winding down at least 30 minutes before your target bedtime.
- Avoid screens and bright lights to help your body produce melatonin.
- Keep a consistent bedtime and wake-up schedule, even on weekends.
- Treat sleep as an essential pillar of your wellness—not an afterthought.
SLEEP AND EXERCISE ARE MORE CONNECTED THAN WE THOUGHT
This study is a reminder that healthy habits don’t exist in isolation. Sleep and physical activity are deeply intertwined, and improving one can often benefit the other.
While more research is needed to untangle all the variables, going to bed earlier is a simple, low-risk experiment that many of us can try. In a world where most people are looking for more energy and better health, an earlier bedtime might be one of the most powerful tools we have.
