People who naturally stay up late tend to think of their night-owl tendencies as a personality quirk or a lifestyle preference. A landmark study published January 28, 2026, in the Journal of the American Heart Association suggests it may also be a cardiovascular risk factor — one that operates over years and compounds with age, particularly in women.
The study, analyzing data from more than 300,000 adults in the UK Biobank, found that people who identified as "definitely evening types" — night owls — had a 79% higher prevalence of overall poor cardiovascular health compared to people with intermediate sleep-wake schedules, and a 16% higher risk of heart attack or stroke over a median follow-up period of about 14 years.
What the Study Measured — and How It Was Done
Researchers reviewed health data for 323,000 adults with an average age of approximately 57 years participating in the UK Biobank — a comprehensive research database that recruited participants from 2006 to 2010 — to assess how chronotype (an individual's natural preference for sleep-wake timing) affected long-term cardiovascular health and risk of major cardiovascular events.
Participants completed a questionnaire rating themselves as definitely morning people, somewhat morning, intermediate, somewhat evening, or definitely evening. About 8% of participants identified as "definitely evening people," characterized by late-night bedtimes (around 2 a.m.) and peak activity later in the day. About 24% were "definitely morning people," with bedtimes around 9 p.m. and earlier peak activity. The remaining 67% fell in the intermediate category.
Cardiovascular health was measured using the American Heart Association's Life's Essential 8™ framework — eight modifiable behavioral and biological factors known to influence cardiovascular health: diet, physical activity, not smoking, sleep quality, healthy body weight, healthy blood glucose, healthy cholesterol levels, and healthy blood pressure. Each participant received a composite score, with a "poor" score indicating significant cardiovascular risk.
The results:
- Night owls were 79% more likely to have an overall poor cardiovascular health score than people with intermediate chronotypes
- Night owls had a 16% higher hazard ratio for heart attack or stroke over nearly 14 years of follow-up, after adjusting for sociodemographic factors, shift work, and family history of CVD
- Over the follow-up period, 18,305 CVD events occurred in the cohort, including 11,091 myocardial infarctions and 7,214 strokes
- The link was stronger among women than among men
| Night Owl Cardiovascular Risk Data | Detail |
| Published in | Journal of the American Heart Association |
| Publication date | January 28, 2026 |
| Participants | 323,000 adults (average age ~57), UK Biobank |
| Follow-up period | Median ~13.8 years |
| Night owls vs. intermediate: poor overall CV health | 79% more likely |
| Night owls vs. intermediate: heart attack or stroke risk | 16% higher hazard ratio |
| Total CVD events in cohort | 18,305 (11,091 MI; 7,214 stroke) |
| Gender-specific finding | Effect stronger in women than men |
| Share of participants who are definite night owls | ~8% |
| Life's Essential 8 domains most impacted for night owls | Smoking exposure (54% more likely to have poor scores); inadequate sleep (42%) |
Why Being a Night Owl Raises Cardiovascular Risk — The Mechanisms
The study does not simply establish that night owls have worse heart health; it identifies the specific pathways through which chronotype elevates risk. Among the eight Life's Essential 8 metrics, night owls scored worse in six. The two strongest associations were with nicotine exposure (night owls were 54% more likely to have poor scores) and inadequate sleep (42% more likely).
According to Medscape's clinical analysis, "it's not just that chronotype alone has something that raises night owls' risk for cardiovascular disease — it is through that profile, or that poor cardiovascular health, that it causes that increased heart disease risk." Night owls also showed worse scores in physical activity, blood glucose, body weight, and diet compared to intermediate chronotypes.
This suggests the elevated cardiovascular risk in night owls is not entirely a direct biological effect of being a night owl — it is partially mediated through lifestyle patterns that tend to cluster in people who are active later in the day. People who stay up late tend to smoke more, sleep less, exercise less, and eat more erratically. The circadian misalignment itself — the mismatch between a night owl's internal clock and the socially imposed demand to be awake and functional early — compounds these effects, producing chronic physiological stress that accumulates over decades.
NBC News quoted the lead author as noting that "future research on chronotype and CVD could develop targeted interventions or personalized messaging to improve patient outcomes, to really see what can work and how much it can decrease risk for night owls."
Heart disease has been the leading cause of death in the United States for more than a century, killing approximately one person every 34 seconds according to the American Heart Association. The AHA did not incorporate sleep into its Life's Essential 8 cardiovascular health framework until 2022, reflecting a relatively recent recognition that sleep quality and timing are as important as diet, exercise, and cholesterol management for heart health.
What Night Owls Can Actually Do About This
The study's finding raises an uncomfortable question: can you change your chronotype? The answer is partially yes. Chronotype has a strong genetic component and is not simply a matter of willpower — but it is also not fixed. Sleep researchers have demonstrated that deliberate, consistent behavioral adjustments — moving the entire sleep schedule earlier by 1 to 2 hours over several weeks — can shift chronotype toward an earlier timing preference, with measurable downstream effects on mood, metabolic health, and cardiovascular risk factors.
The most evidence-based steps for night owls who want to reduce cardiovascular risk include:
- Setting a consistent wake time and sticking to it, including weekends — the anchor for shifting circadian timing
- Increasing morning light exposure immediately upon waking, which advances the biological clock
- Avoiding bright screens (phones, tablets, TVs) in the two hours before an earlier target bedtime
- Moving vigorous exercise earlier in the day — evening workouts can delay sleep timing
- Reducing alcohol and caffeine in the afternoon and evening, both of which can delay sleep onset and reduce sleep quality
- Aiming for 7 to 9 hours of sleep, as the Life's Essential 8 framework recommends
The 2026 study's findings reinforce what the AHA's Life's Essential 8 framework has formally recognized: sleep is not a passive recovery process but an active component of cardiovascular health, as modifiable as diet, exercise, or blood pressure.
Frequently Asked Questions
What did the night owl heart disease study find?
Published January 28, 2026, in the Journal of the American Heart Association, the study of 323,000 UK Biobank participants found that people who identified as definite night owls had a 79% higher prevalence of poor overall cardiovascular health (per Life's Essential 8) and a 16% higher risk of heart attack or stroke over a median of ~14 years of follow-up, compared to intermediate chronotypes.
Why are night owls at higher cardiovascular risk?
The elevated risk appears to be mediated primarily through lifestyle factors that cluster in night owls — particularly higher rates of smoking, inadequate sleep, reduced physical activity, and less healthy diet — rather than a direct biological effect of sleep-wake timing. Circadian misalignment (the mismatch between an internal biological clock and societal schedules) compounds these effects over years.
Are women at higher risk than men?
The study found the association between evening chronotype and worse cardiovascular health was stronger in women than in men. Researchers suggest this may reflect differences in circadian biology or social factors, but the specific mechanisms are under ongoing investigation.
Can you change your chronotype?
Partially. Chronotype has a genetic component but is not fixed. Consistent earlier wake times, morning light exposure, evening screen reduction, earlier exercise, and reduced evening caffeine and alcohol can shift chronotype toward earlier timing over weeks, with downstream effects on sleep quality and cardiovascular risk factors.
How is chronotype related to sleep apnea?
Night owls tend to get less total sleep and may have higher rates of sleep disruption, both of which independently elevate cardiovascular risk. Obstructive sleep apnea — which is associated with a fourfold increase in all-cause mortality — is not directly caused by chronotype but can worsen the sleep quality and cardiovascular risk profile of night owls.
