We’ve all had a few rough nights where sleep takes a backseat—whether it’s work, worry, or binge-watching just one more episode. But new research from Sweden suggests that even short-term sleep loss can set off biological changes linked to heart disease.

The study, led by Uppsala University and published in Biomarker Research, zoomed in on what happens at the molecular level when healthy young adults get too little sleep. The results were that just a few nights of sleep deprivation triggered increases in dozens of proteins associated with inflammation and cardiovascular risk.

It’s already well-known that chronic poor sleep is linked to heart attacks, stroke, and arrhythmias like atrial fibrillation. But many studies have focused on older adults or people already at risk.

Researchers recruited 16 healthy young men with normal weight and good sleep habits, then brought them into a highly controlled sleep lab. Over two sessions, participants followed identical diets and activity levels, but in one session they slept normally, and in the other they got just four hours of sleep a night for three nights.

Using blood tests to screen around 90 different proteins, the researchers found that many of the proteins tied to inflammation rose after just three nights of short sleep. Some of these proteins have already been linked to heart failure and coronary artery disease in prior research.

“It was interesting that the levels of these proteins increased in the same way in younger and previously perfectly healthy individuals after only a few nights of sleep deprivation,” said Cedernaes.“This means that it’s important to emphasize the importance of sleep for cardiovascular health even early in life.”

Exercise Still Helps—But It’s Not a Replacement

The good news: even sleep-deprived participants still saw increases in proteins associated with the benefits of exercise. In other words, hitting the treadmill still triggers helpful molecular responses, even if you’re sleep-deprived.

But there’s a catch.

“Studies have also shown that physical exercise can offset at least some of the negative effects that poor sleep can cause,” said Cedernaes.

“But it’s also important to note that exercise cannot replace the essential functions of sleep.”

So while workouts help, they aren’t a substitute for giving your body and brain a full night to recover and reset.

While this study doesn’t mean the occasional late night will doom your heart, it does suggest that sleep quality matters more—and earlier—than many people realize. The results of this study adds further biological evidence to the growing chorus of experts saying sleep should be treated as seriously as diet and exercise when it comes to heart health.

So if you’ve been brushing off sleep as optional self-care, consider this your science-backed reminder, DON’T! Sleep forms the backbone of health and wellness, and it should not be viewed as secondary or something you do when you die.

LEM Brandao et al. The overlooked trio: sleep duration, sampling time and physical exercise alter levels of olink-assessed blood biomarkers of cardiovascular risk. Biomarker Research (2025). DOI: 10.1186/s40364-025-00776-0