Want to burn more calories? New study reveals surprising link between sleep time and daily activity

Economic Times

03-07-2025

Researchers have found a strong link between earlier bedtimes and increased physical activity, using data from nearly 20,000 participants. Even a two-hour shift toward earlier sleep resulted in noticeable fitness benefits. The findings suggest health campaigns should integrate sleep timing with exercise promotion to improve public health and encourage more active lifestyles.
A study published in the Proceedings of the National Academy of Sciences reveals that people who go to bed earlier tend to be significantly more active the next day. (Image:iStock)
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In the world of wellness , we often separate sleep and exercise into different compartments. But what if your bedtime was actually the secret driver of your daily physical activity ? A new study published in the Proceedings of the National Academy of Sciences suggests just that—going to bed earlier could be the simplest way to get more active.According to a report from Health Day, the research, led by scientists from Monash University in Australia, tracked nearly 20,000 individuals over a year using wearable sleep-and-activity trackers. The average bedtime hovered around 11 p.m., but those who tucked in by 9 p.m. consistently logged about 30 more minutes of moderate-to-vigorous physical activity the following day than those who stayed up until 1 a.m.Even small shifts mattered. Going to bed at 9 p.m. instead of 11 p.m. translated into nearly 15 extra minutes of physical activity, highlighting how tightly sleep timing is linked to movement the next day.'Sleep and physical activity are both critical to health, but until now we didn't fully grasp how intricately connected they are in everyday life,' said Dr. Elise Facer-Childs, senior research fellow at Monash University's School of Psychological Sciences, in the university's press release.The data didn't just stop at bedtime. Researchers also noted that standard 9-to-5 work routines may unintentionally work against our natural sleep rhythms—especially for those who are biologically inclined to stay up late. This mismatch, often referred to as 'social jetlag,' can lead to poorer sleep quality, daytime fatigue, and ultimately less motivation to exercise.'Standard 9-to-5 routines can clash with the natural sleep preferences of evening types,' said lead researcher Josh Leota. 'This leads to poorer sleep quality and increased daytime sleepiness—which can all reduce motivation and opportunity for physical activity the next day.'The findings were validated with additional Fitbit data from another cohort of nearly 6,000 participants, strengthening the argument that sleep timing isn't just a fringe factor in your fitness—it may be central to it.One of the most promising insights from the study is that the cycle isn't fixed. Participants who shifted to earlier bedtimes—while maintaining the same total sleep duration—were the ones who recorded the highest levels of activity the following day.In other words, you don't need more sleep, just smarter sleep.'Rather than just promoting sleep and physical activity independently, health campaigns could encourage earlier bedtimes to naturally foster more active lifestyles,' Leota explained, suggesting a more integrated approach to public health messaging.If you're trying to become more consistent with your workouts or just want to boost your daily activity, it might be time to re-evaluate what time you're hitting the sack. As this study shows, making peace with your pillow a little earlier could be the most underrated fitness strategy out there.So the next time you're tempted to binge another episode or scroll through social media past midnight, remember—your morning workout might thank you for calling it a night.