We all know the drill. Get seven to nine hours of sleep. Walk at least 8,000 steps a day. Simple enough, right? Except a massive new study reveals that almost nobody actually does both. And maybe that’s because we’ve been thinking about this backwards the whole time.
Researchers at Flinders University in Australia tracked real health data from over 70,000 people worldwide. We’re talking about 28 million days of actual measurements, not surveys where people guess how much they slept or walked. The results? Less than 13 percent of us consistently hit both targets. Meanwhile, 17 percent are stuck in a tough spot: under seven hours of sleep and fewer than 5,000 steps per day. That combination raises serious risks for chronic disease, weight gain, and mental health problems.
Think about your typical day. Work deadlines pile up. Family needs attention. You want some time to yourself. Where does a full night’s sleep and a long walk fit in? For most of us, it doesn’t. We end up tired and inactive, caught in a frustrating loop.
Here’s where things get interesting. For years, health experts told us exercise helps you sleep better, which gives you energy to exercise more. Sounds logical. But this study found something different. The relationship works much better in one direction than the other.
Sleep Drives Activity More Than Activity Drives Sleep
The research team tracked people’s sleep and steps for three and a half years using regular fitness devices. They wanted to know: Does walking 10,000 steps today help you sleep better tonight? And does sleeping well tonight make you walk more tomorrow?
The answer surprised them. Sleep quality predicted next-day activity far better than activity predicted next-night sleep. Lead researcher Josh Fitton put it plainly:
“We found that getting a good night’s sleep – especially high-quality sleep – sets you up for a more active day,” says Mr Fitton, a PhD candidate at FHMRI Sleep Health.
Your brain needs rest to feel motivated. A tired mind doesn’t want to move, no matter how many health benefits you know exercise provides. Fitton added that “People who slept well tended to move more the following day, but doing extra steps didn’t really improve sleep that night. This highlights the importance of sleep if we want to boost physical activity.”
The study also found something odd about sleep duration. People who slept six to seven hours logged the most steps the next day, not those who slept nine hours. Does this mean less sleep is better? No. What matters most is sleep efficiency, how much of your time in bed you actually spend resting. Tossing and turning for nine hours doesn’t help. Six hours of solid sleep does more good.
Maybe Our Health Goals Are Unrealistic
Professor Danny Eckert, who led the research team, thinks these findings challenge our basic assumptions. Is it even realistic to expect people to max out both sleep and activity every single day? The data says most of us can’t manage it. And maybe that’s okay.
Current health recommendations don’t account for this reality. They treat sleep and exercise as separate goals. But they’re connected. And for most people, they compete for the same limited hours. When you have to choose between an early workout or an extra hour of sleep, this research suggests sleep wins.
Professor Eckert offers straightforward advice for anyone feeling overwhelmed:
“Prioritising sleep could be the most effective way to boost your energy, motivation and capacity for movement,” says Professor Eckert.
This isn’t about adding more tasks to your day. It’s about protecting your rest. Simple changes help: less screen time before bed, consistent sleep times, a quiet bedroom. These small adjustments make real differences.
Sleep isn’t downtime. It’s preparation. When you sleep well, you wake up ready to move. That’s how 87 percent of us who struggle with these goals might finally make progress. Fix your sleep first. The activity will follow.
The article, “Bidirectional associations between sleep and physical activity investigated using large-scale objective monitoring data,” by Josh Fitton, et al., was published in Communications Medicine.
Communications Medicine: 10.1038/s43856-025-01226-6
ScienceBlog.com has no paywalls, no sponsored content, and no agenda beyond getting the science right. Every story here is written to inform, not to impress an advertiser or push a point of view.
Good science journalism takes time — reading the papers, checking the claims, finding researchers who can put findings in context. We do that work because we think it matters.
If you find this site useful, consider supporting it with a donation. Even a few dollars a month helps keep the coverage independent and free for everyone.