Staying Up Late Could Quietly Damage Your Heart

Research Highlights:

• Adults in midlife and older age who tend to be most active in the evening, especially women, showed poorer overall heart health compared with those who did not strongly prefer mornings or evenings, based on the American Heart Association’s Life’s Essential 8 score.
• The analysis of UK Biobank data suggests that common habits among night owls, including lower diet quality, too little sleep, and higher rates of smoking, help explain why their cardiovascular health scores were lower.
• Researchers say these findings also point to opportunity, since improving sleep, diet, and other daily habits could help night owls reduce their chances of heart attack and stroke.

Evening Activity Linked to Poorer Heart Health

Adults in middle age and beyond who tend to be more active later in the day were found to have worse heart health than those who are more active earlier. The effect appeared to be particularly strong among women, according to new findings published today (January 28) in the Journal of the American Heart Association, an open-access, peer-reviewed journal of the American Heart Association.

The research suggests that when people prefer to stay active and awake may play an important role in long-term cardiovascular health.

Large UK Study Examines Sleep Timing and the Heart

Scientists analyzed health information from more than 300,000 adults (average age of about 57 years) who took part in the UK Biobank. The goal was to understand how chronotypes, or a person’s natural sleep and wake preference, relate to measures of heart health.

Participants were grouped based on how they described their daily rhythms. About 8% identified as “definitely evening people,” meaning they usually went to bed very late (for example, 2 a.m.) and were most active later in the day. Roughly 24% described themselves as “definitely morning people,” who tended to wake up earlier, go to bed earlier (for example, 9 p.m.), and be most active earlier in the day. The remaining 67% fell into an “intermediate” group if they were unsure or said they were neither clearly a morning nor evening person.

How Cardiovascular Health Was Measured

Heart health was assessed using the American Heart Association’s Life’s Essential 8 metrics. These criteria focus on behaviors and health factors linked to strong cardiovascular health, including nutritious eating, regular physical activity, not smoking, and getting good-quality sleep. The scoring system also accounts for healthy levels of body weight, cholesterol, blood sugar, and blood pressure.

Key Findings on Night Owls and Heart Risk

When researchers compared the different chronotype groups, several clear patterns emerged:

• Evening chronotypes had a 79% higher likelihood of receiving an overall poor cardiovascular health score compared to those in the intermediate group.
• Night owls also showed a 16% greater risk of experiencing a heart attack or stroke during a median follow-up period of about 14 years.
• The link between evening preference and lower heart health scores was stronger in women than in men.
• Much of the added heart disease risk among evening types was connected to lifestyle factors, especially nicotine use and insufficient sleep.
• In contrast, people who identified as morning types had a 5% lower prevalence of poor heart health scores compared with those who did not strongly identify as morning or evening oriented.

Why Evening Schedules May Affect the Heart

“‘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, Ph.D., D.V.M.; a research fellow in the division of sleep and circadian disorders at Brigham and Women’s Hospital and Harvard Medical School, both in Boston. “Evening people may be more likely to have behaviors that can affect cardiovascular health, such as poorer diet quality, smoking, and inadequate or irregular sleep.”

This mismatch between biological rhythms and daily routines may help explain why late sleepers face added challenges when it comes to heart health.

Health Risks Are Not Set in Stone

The results do not mean that night owls are destined to have poor heart health, according to Kristen Knutson, Ph.D., FAHA, volunteer chair of the 2025 American Heart Association statement, Role of Circadian Health in Cardiometabolic Health and Disease Risk. Knutson was not involved in the study.

“These findings show that the higher heart disease risks among evening types are partly due to modifiable behaviors such as smoking and sleep. Therefore, evening types have options to improve their cardiovascular health,” she said. “Evening types aren’t inherently less healthy, but they face challenges that make it particularly important for them to maintain a healthy lifestyle.”

Tailoring Care to Body Clocks

The American Heart Association scientific statement led by Knutson highlights the importance of considering chronotype when planning health interventions or treatments.

“Some medications or therapies work best when they align with a specific time of relevant circadian rhythms, and this time will vary depending on whether you are a morning, intermediate, or evening chronotype,” she said. “Targeted programs for people who naturally stay up late could help them improve their lifestyle behaviors and reduce their risk of cardiovascular disease.”

Study Limitations to Keep in Mind

The researchers noted several limitations. Most participants in the UK Biobank were white people and generally healthier than the broader population, which may limit how well the findings apply to other groups. In addition, chronotype was measured only once and relied on self-reported responses, rather than repeated or objective assessments.

Reference: “Chronotype, Life’s Essential 8, and Risk of Cardiovascular Disease: A Prospective Cohort Study in UK Biobank” by Sina Kianersi, Kaitlin S. Potts, Heming Wang, Tamar Sofer, Raymond Noordam, Martin K Rutter, Kathryn Rexrode, Susan Redline and Tianyi Huang, 28 January 2026, Journal of the American Heart Association.
DOI: 10.1161/JAHA.125.044189

Co-authors, disclosures and funding sources are listed in the manuscript. The study was partially funded by the American Heart Association.

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