Middle-aged and older adults who were more active in the evenings had poorer cardiovascular health than those whose activity was concentrated earlier in the day, with the association appearing particularly strong among women, according to new research published in the Journal of the American Heart Association.
Researchers analysed health data from more than 300,000 adults taking part in the UK Biobank (average age around 57 years) to examine how chronotype (an individual’s natural preference for sleep and wake timing) influences cardiovascular health.
Around 8% of participants identified as “definitely evening people”, typically going to bed late (for example, 2 a.m.) and reaching peak activity later in the day. About 24% described themselves as “definitely morning people”, with earlier bedtimes (around 9 p.m.) and greater activity earlier in the day. The remaining 67% were classified as having an “intermediate” chronotype, meaning they did not strongly identify with either pattern.
Cardiovascular health was assessed using the American Heart Association’s Life’s Essential 8™ metrics, which evaluate behaviours and clinical factors linked to optimal heart health. These include diet quality, regular physical activity, smoking status, sleep health, and healthy levels of weight, cholesterol, blood glucose and blood pressure.
The analysis showed that:
- Compared with intermediate types, evening chronotypes had a 79% higher prevalence of poor overall cardiovascular health scores.
- Night owls had a 16% greater risk of heart attack or stroke during a median follow-up of about 14 years.
- The link between evening chronotype and poor heart health was stronger in women than in men.
- Much of the increased cardiovascular risk among evening types was explained by less healthy behaviours, particularly smoking and insufficient sleep.
- In contrast, morning types had a 5% lower prevalence of poor heart health scores compared with intermediate types.
Evening types often experience circadian misalignment, where their internal body clock does not match the natural light–dark cycle or typical daily schedules. This misalignment may contribute to behaviours that negatively affect cardiovascular health, such as poorer diet quality, smoking, and inadequate or irregular sleep.
However, experts note that the findings are not entirely discouraging for night owls. Much of the risk appears to be modifiable. These results suggest that the increased heart disease risk among evening types is partly driven by behaviours such as smoking and poor sleep, which can be changed. Evening types are not inherently less healthy, but they may face challenges that make maintaining healthy habits especially important.
The scientific statement also recommends considering chronotype when planning treatments or lifestyle interventions. Some medications and therapies may be more effective when timed to align with an individual’s circadian rhythms, which differ between morning, intermediate and evening types.
Tailored approaches for people who naturally stay up late could help improve their lifestyle habits and reduce their risk of cardiovascular disease.
Source: American Heart Association
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