Scientists Say If You Have to Choose Between Working Out And Sleeping, You Should Always Pick Sleep. Here’s Why

A new study says only 13 percent of people sleep enough and move enough at the same time.

Getting enough sleep and staying active are the cornerstones of good health. Yet, a massive new study from Flinders University reveals that most of us are failing on both fronts.

The researchers, led by PhD candidate Josh Fitton from Flinders University, analyzed over 28 million days of objective health data to figure out how sleep and physical activity truly interact. The results are humbling. Only a tiny minority, 12.9% of people, routinely hit the recommended health targets of seven to nine hours of sleep and over 8,000 steps daily.

However, the researchers found that moving more won’t necessarily help you sleep better, but sleeping better will absolutely make you move more the next day.

So, if you can only pick one — exercise the next day or sleep well — your safest bet is to choose sleep.

The Sleepless, Step-less Majority

The study used objective data collected over three and a half years from 70,963 users of consumer devices, specifically an under-mattress sleep sensor and a wrist-worn health tracker, across 244 geographical regions. This volume of “big data” allowed the team to map the daily interplay between sleep and physical activity.

The findings, published in Communications Medicine, show that fewer than 13% of people consistently meet recommended targets for both sleep and physical activity. Even this small percentage may be inflated, as the authors caution that the sleep sensor they used tends to overestimate sleep duration (sometimes by up to 30 min) compared to gold-standard testing in the lab.

It could be worse, though. A significant chunk of the global sample (16.5%) is at high risk because they averaged less than seven hours of sleep and fewer than 5,000 steps per day. This combination of poor sleep and poor exercise is linked to higher risks of chronic disease, weight gain, and mental health issues.

The Wake-Up Call: Sleep Drives Activity

The researchers found that the link between rest and movement is primarily unidirectional. “We found that getting a good night’s sleep — especially high-quality sleep — sets you up for a more active day,” said Fitton, a PhD candidate at Flinders Health and Medical Research Institute (FHMRI) Sleep Health.

In other words, the better you sleep, the more you move. But the reverse isn’t true — logging extra steps doesn’t seem to improve your sleep that night.

The “sweet spot” for next-day activity was around six to seven hours of sleep. So, the longest snooze is not necessarily optimal. People who slept this amount tended to rack up the most steps the following day — about 300 more than those who slept eight hours. But before you cut your sleep short, the authors stress that quality is just as important as duration. Those with higher sleep efficiency — meaning they spent less time tossing and turning — consistently moved more the next day.

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This finding supports the 24-hour activity cycle concept, which views sleep and physical activity as interconnected, temporally dependent components of health. This new data suggests sleep is the dominant driver within this cycle.

Senior author Professor Danny Eckert advises that for people juggling family and work, focusing on rest should be the first step toward a healthier life. “Prioritising sleep could be the most effective way to boost your energy, motivation and capacity for movement,” Eckert noted.

A Global Snapshot of Exhaustion

Across the sample, participants averaged 7.1 hours of sleep and 5,521 steps per day. That’s far below the 8,000-step benchmark linked to lower risks of chronic illness.

But no matter where people lived or how old they were, the big picture stayed the same: the vast majority struggle to sleep enough and move enough at the same time.

Since only a tiny fraction of the population can achieve both, the researchers stress the need to ensure global sleep and physical activity recommendations are mutually attainable.

“Our findings call into question the real-world compatibility of prominent health recommendations and highlight how difficult it is for most people to have an active lifestyle and sleep well at the same time,” Fitton said.

Professor Eckert’s message is that sleep must be viewed differently. “Our research shows that sleep is not just a passive state, it’s an active contributor to your ability to live a healthy, active life,” he said.

The path to a more active life, he suggests, may begin with simple changes: reducing screen time before bed, keeping a consistent bedtime, and creating a calm sleep environment. Integrated health interventions that prioritize sleep first are likely to be the most effective way to help people meet both goals.