I’ve always been a bit of a night owl. I’m always so busy with work and errands during the day that late evening is the only time I have to myself to watch TV, read or just chill out.
I never considered what my late-night habits might be doing to my health. I figured as long as I was still getting eight hours of sleep every night, I was fine, right?
Wrong. Turns out night owls like me might be raising their risk of type 2 diabetes, non-alcoholic fatty liver disease and depression.
Plus, staying up late could be doing a number on my heart…
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Late nights and heart risks
A team of international researchers reviewed health data from more than 300,000 UK Biobank participants aged 57 on average to assess the impact of chronotypes on heart health.
A chronotype is an individual’s natural preference for sleep-wake timing — in other words, whether they’re a morning person or a night owl…
- About 8% of participants identified as “definitely evening people,” characterized by a late-night bedtime (e.g., 2 a.m.) and peak activity later in the day.
- About 24% of participants said they were “definitely morning people,” more active earlier in the day and with earlier bedtimes (for example, 9 p.m.).
- Roughly two-thirds of participants were classified as an “intermediate” chronotype, having replied either that they were unsure or that they were neither a morning person nor an evening person.
The researchers measured cardiovascular health using the American Heart Association’s Life’s Essential 8™ metrics, which note behaviors and factors associated with optimal heart health. The metrics include a healthy diet, regular physical activity, not smoking and getting quality sleep, as well as healthy weight, cholesterol, blood sugar and blood pressure numbers.
The findings were sobering. Compared to intermediate chronotypes, evening people had a whopping 79% higher likelihood of having a poor overall cardiovascular health score.
Worse, night owls had a 16% higher risk of having a heart attack or stroke over a median of about 14 years of follow-up compared to those in the intermediate category.
Much of the evening chronotype’s increased risk of heart disease was due to poor heart health habits and factors, especially nicotine use and inadequate sleep.
Interestingly, women in the evening chronotype were more likely to have low cardiovascular scores than men.
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So what’s at the core of worse heart scores for night owls?
According to lead study author Dr. Sina Kianersi, a research fellow in the division of sleep and circadian disorders at Brigham and Women’s Hospital and Harvard Medical School, “‘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.
“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,” Kianersi adds.
By contrast, early birds had a 5% lower prevalence of low heart health scores compared with those in the intermediate chronotype.
Heart risk can be managed
Not all the news is bad, however, according to Dr. Kristen Knutson, 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 research, but shared that, “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. Evening types aren’t inherently less healthy, but they face challenges that make it particularly important for them to maintain a healthy lifestyle.”
Some challenges that come along with late nights may include some unhealthy habits. Night owls often experience intense cravings and reach for highly processed, high-carb junk foods. The “night owl lifestyle” is also associated with higher consumption of alcohol. Night owls are also more likely than early birds to be smokers.
But indirect challenges to heart health that night owls face include exposure to electronics and artificial light at night. This perpetuates circadian disruption and is linked to higher blood pressure and inflammation.
Late nights can also add up to higher cortisol and elevated stress levels, which contribute to risks for heart problems.
So, what can night owls like me do to protect our heart health? Work on our sleeping habits — but remember, there are many other ways to support heart health, like the diet that improved heart health in just 8 weeks!
There were limitations to the study. Most UK Biobank participants were white and generally healthier than the broader population, and the findings for other groups may be limited. Plus, evening vs. morning preference was self-reported and measured only once.
Sources:
Being a night owl may increase your heart risk — American Heart Association
Chronotype, Life’s Essential 8, and Risk of Cardiovascular Disease: A Prospective Cohort Study in UK Biobank — Journal of the American Heart Association
Late bedtimes are linked to higher heart disease risk — ScienceDaily
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