Prefer late nights? Study links late bedtimes to heart disease risk

Late-night routines may quietly affect heart health, with researchers finding higher cardiovascular risk among people who prefer staying up late

In our always-on world, countless people stay up late, working, scrolling through social media or binge-watching shows. But could those late nights silently harm your heart? A major new study suggests they just might. The research, published in the Journal of the American Heart Association, finds that people who are 'night owls' face a significantly higher risk of poor cardiovascular health, including heart attack and stroke.

 

What did researchers do in the study?

 

In the study, titled “Chronotype, Life’s Essential 8, and Risk of Cardiovascular Disease: A Prospective Cohort Study in UK Biobank,” researchers drew on data from the UK Biobank, tracking more than 322,000 adults aged 39-74 years over nearly 14 years.

 

Participants were categorised by chronotype, essentially whether they see themselves as morning-loving “larks”, evening-oriented “night owls”, or somewhere in between.

 

The heart health of participants was measured using Life’s Essential 8, a scoring system developed by the American Heart Association that assesses eight key factors, including sleep, diet, smoking, physical activity, blood pressure, cholesterol, body weight and blood sugar.

 

Key findings: Night owls at higher risk

 

The results showed clear differences between chronotypes.

 

• Evening chronotypes were 79 per cent more likely to have poor overall cardiovascular health than intermediate types.
• Night owls faced a 16 per cent higher risk of heart attack or stroke over a median follow-up of nearly 14 years.
• The association between late-night preference and poorer heart health was stronger in women than in men.
• The increased risk among evening types was largely linked to lifestyle factors, particularly nicotine use and inadequate sleep.
• Morning types showed a 5 per cent lower prevalence of poor heart health scores compared with those without a strong chronotype preference.

 

It’s important to stress that night-time activity itself isn’t necessarily the direct cause of heart disease; rather, late sleepers often have lifestyle habits that contribute to poorer heart health.

 

"These findings show that the higher heart disease risks among evening types are partly due to modifiable behaviours such as smoking and sleep. Therefore, evening types have options to improve their cardiovascular health," said Kristen Knutson, Chair and lead author of the 2025 American Heart Association (AHA) scientific statement, Role of Circadian Health in Cardiometabolic Health and Disease Risk. Knutson was not involved in the study.

 

Why might staying up late be risky?

 

Internal clock vs outside world

Your body has an internal clock, a circadian rhythm that regulates sleep, metabolism, blood pressure and more. When your sleep schedule clashes with the typical day–night cycle, this circadian misalignment can disrupt more than just your energy levels, which is why night owls may feel tired during conventional hours.

This mismatch can make it harder to maintain regular meals, exercise routines and sleep patterns. Over time, such misalignment appears to affect metabolic and cardiovascular functions.

 

"'Evening people' often experience circadian misalignment, meaning their internal body clock may not match the natural day-to-night light cycle or their typical daily schedules," said lead study author Sina Kianersi, research fellow, Sleep and circadian disorders at Brigham and Women's Hospital and Harvard Medical School, Boston.

 

Unhealthy habits can creep in

From grabbing sugary snacks late at night to reaching for cigarettes or caffeine to stay awake, night owls often accumulate unhealthy habits that further raise their heart risk.

"Evening people may be more likely to have behaviours that can affect cardiovascular health, such as poorer diet quality, smoking and inadequate or irregular sleep," added Kianersi.

 

Simple ways to protect your heart

 

The good news is that the increased heart risk linked with staying up late isn’t inevitable. Many of the contributing factors are modifiable. Here are practical steps highlighted by the researchers:

 

• Aim for consistent wake/sleep times: Even if you prefer evenings, a regular schedule and getting some morning sunlight support your internal clock.
• Prioritise quality sleep: Getting enough hours makes a big difference.
• Focus on diet and physical activity: Heart-health improvements here can offset other risks.
• Manage blood pressure, cholesterol and blood sugar: Routine health checks can catch issues early.
• Avoid tobacco and limit alcohol and nicotine exposure: These remain key risk factors for heart disease.

 

The American Heart Association statement led by Knutson also advises considering chronotype when planning treatment or lifestyle changes. Some therapies work best when timed to a person’s internal clock, which differs between morning and evening types. Targeted programmes for night owls could help improve habits and lower heart disease risk, she added.   

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This report is for informational purposes only and is not a substitute for professional medical advice.