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You set your alarm for an early-morning workout because you know you should exercise. But when the alarm goes off, your body feels heavy and exhausted. Should you skip the workout and get a little more sleep—or force yourself out of bed and exercise? The decision can be even harder when you barely slept the night before.

Both sleep and exercise are essential to good health, so giving up either one isn't ideal. But a fascinating study that tracked the daily habits of about 71,000 people over three and a half years found an unexpected pattern: being more physically active did not necessarily mean sleeping better that night. However, people who slept well tended to be more physically active the following day.

Researchers at Flinders University in Australia analyzed data from 70,963 people collected between January 2020 and September 2023. Participants used an under-mattress sleep sensor and a wrist-worn activity tracker to monitor their sleep and physical activity. The findings were published last year in the international journal Communications Medicine.

People Who Slept Well Were More Active the Next Day

One of the most interesting findings was the relationship between sleep and activity levels the following day.

According to a recent article in Men's Health that highlighted the study, people who got enough sleep walked about 8,000 steps per day on average, while those who didn't get enough sleep averaged only around 5,000 steps.

That's a substantial difference in overall daily movement.

The study also found considerable overlap between short sleep and low activity levels. Among participants, 12.9% both slept 7–9 hours and walked at least 8,000 steps a day. By comparison, 16.5% slept fewer than 7 hours and walked fewer than 5,000 steps.

Of course, this does not mean that sleeping less automatically causes someone to walk 3,000 fewer steps. Because this was an observational study, it cannot establish that insufficient sleep directly causes lower physical activity. Other factors, including lifestyle habits, may also have played a role.

Still, the study revealed a clear pattern: the relationship between sleep and next-day physical activity appeared to be stronger in the direction of sleep affecting activity the following day than activity affecting sleep that night.

Cutting Sleep Short to Exercise May Not Be the Best Strategy

What's particularly interesting about these findings is that they challenge the way we often think about exercise and sleep.

We tend to assume that exercising makes us tired and therefore helps us sleep better. And in fact, regular exercise can benefit sleep health. But this study also found a strong pattern in the opposite direction: getting good sleep may help you stay more active the next day.

That means it may be worth reconsidering the habit of cutting into your sleep just to make time for exercise.

For example, if you wake up an hour earlier than usual to work out but end up feeling exhausted throughout the day and moving less overall, you may have gained one workout while losing a significant amount of activity over the rest of the day.

This may be especially relevant for people who don't have much time for formal exercise.

Physical activity doesn't happen only at the gym or during a run. Walking, taking the stairs, doing household chores, running errands, and simply moving around throughout the day all contribute to your overall activity level.

So, Should Sleep Come Before Exercise?

This study does not mean that sleep is always more important than exercise. Sleep and physical activity are both important health habits, and because this was an observational study, the findings cannot establish a simple cause-and-effect relationship.

However, instead of sacrificing sleep to create more time for exercise, it may be worth prioritizing enough sleep so that you're physically ready to move the next day.

If you wake up feeling sluggish after a poor night's sleep, you don't necessarily have to push yourself through a high-intensity workout. Taking a longer walk during your commute, choosing the stairs, or simply finding more opportunities to move throughout the day can be another way to stay active.

The goal isn't to choose between sleep and exercise. It's to avoid turning sleep deprivation into a strategy for finding more time to work out.

Getting enough sleep may not be taking time away from tomorrow's activity. It may be what helps your body move more the next day.

Source: 헬스조선  (https://health.chosun.com/site/data/html_dir/2026/09/18/2026091801988.html)