People who naturally stay up late may face a higher risk of poor cardiovascular health, according to new research examining how sleep-wake patterns relate to heart health.

The study, published in the Journal of the American Heart Association, analysed health information from more than 300,000 adults in the UK Biobank, with an average age of about 57. Researchers assessed participants according to their chronotype.

Around 8% described themselves as 'definitely evening people', while about 24% identified as 'definitely morning people'. Most participants, around 67%, were classified as having an intermediate chronotype.

What Did the Study Find?

The researchers found that people with an evening chronotype were more likely to have poorer cardiovascular health than those without a strong morning or evening preference.

Night owls had a 79% higher prevalence of overall poor cardiovascular health, based on the American Heart Association's Life's Essential 8 measures. These include diet, physical activity, smoking, sleep, body weight, cholesterol, blood sugar, and blood pressure.

The study also found that evening types had a 16% higher risk of heart attack or stroke over a median follow-up period of about 14 years compared with people with an intermediate chronotype. The association between an evening chronotype and poorer cardiovascular health was stronger among women than men.

However, the findings do not mean that simply going to bed late will inevitably cause heart disease.

Why Might Staying Up Late Affect Heart Health?

One possible explanation is circadian misalignment, when the body's internal biological clock does not align well with environmental cues such as daylight or with a person's daily schedule.

'Evening people' may also be more likely to experience behaviours that can negatively affect cardiovascular health, including inadequate or irregular sleep, poorer diet quality and smoking, according to lead study author Sina Kianersi, PhD, DVM.

The researchers found that these potentially modifiable factors, accounted for much of the increased cardiovascular risk seen among evening types, including factors such as nicotine use and insufficient sleep.

This distinction is important. Being naturally inclined towards later nights does not automatically mean someone has poor heart health. Kristen Knutson, PhD, FAHA, who was not involved in the study, said evening types 'aren't inherently less healthy', but may face challenges that make healthy lifestyle habits particularly important.

Does Sleeping Late Mean You Will Have a Heart Attack?

Not necessarily. The study identified an association, rather than proving that an evening chronotype directly causes heart attacks or strokes. Researchers also noted several limitations, including the fact that chronotype was self-reported and measured only once.

Most UK Biobank participants were also white and generally healthier than the wider population, meaning the findings may not apply equally to everyone.

Other factors, including age, genetics, existing health conditions, work schedules, diet, physical activity, and smoking, can influence cardiovascular risk.

What Can Night Owls Do to Protect Their Hearts?

People who naturally prefer later nights do not necessarily need to force themselves into an early-morning routine. Instead, focusing on consistent and healthy habits may be more useful.

Getting enough sleep, maintaining a regular sleep schedule, exercising regularly, eating a balanced diet, avoiding tobacco, and keeping blood pressure, cholesterol, and blood sugar under control can all contribute to better cardiovascular health.

The findings suggest that the quality and consistency of lifestyle habits may matter more than simply whether someone identifies as a night owl.

For people who regularly struggle to sleep, feel excessively tired during the day, or find their sleep schedule difficult to control, speaking with a healthcare professional may help identify underlying sleep problems.

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