Night Owls and Cardiovascular Health: New Insights from UK Biobank

Adults who naturally prefer late bedtimes may have poorer cardiovascular health than those who wake earlier, according to a large prospective analysis from the UK Biobank recently published in the Journal of the American Heart Association.

Study Overview

The study included 322,777 adults aged 39–74 years with no known cardiovascular disease (CVD) at baseline and followed them for a median of 13.8 years. Participants self-identified their chronotype as definite evening, definite morning, or intermediate.

Chronotype reflects an individual’s intrinsic circadian preference for sleep–wake timing and may indicate underlying circadian misalignment when daily behaviors do not align with internal biological rhythms.

Key Findings

Participants with a definite evening chronotype demonstrated substantially poorer cardiovascular health as measured by the American Heart Association’s Life’s Essential 8 (LE8) score. Compared with the intermediate group, evening types had a 79% higher prevalence of poor LE8 scores, while definite morning types showed a 5% lower prevalence.

Approximately 75% of the excess cardiovascular risk observed among evening chronotypes was attributable to modifiable lifestyle and metabolic factors, including diet quality, physical activity, smoking status, sleep health, body weight, blood glucose, cholesterol, and blood pressure.

Drivers of Risk

Among the LE8 components, the strongest associations with evening chronotype were observed for:

• Nicotine exposure (prevalence ratio 1.54)

• Inadequate sleep (prevalence ratio 1.42)

Smaller but consistent associations were also seen for physical inactivity, impaired glucose control, higher body weight, and suboptimal diet quality. In contrast, associations with blood pressure and cholesterol levels were minimal.

Cardiovascular Outcomes

During follow-up, 18,305 cardiovascular events were recorded, including 11,091 myocardial infarctions and 7,214 strokes. After adjustment for sociodemographic factors, shift work, and family history of CVD, individuals with a definite evening chronotype had a 16% higher risk of total CVD compared with those with an intermediate chronotype. No statistically meaningful increase in risk was observed among definite morning types.

Clinical and Research Implications

The findings reinforce the close relationship between sleep patterns, circadian biology, and cardiovascular health. While the observational nature of the study precludes causal conclusions, evening chronotype may help identify individuals who could benefit from earlier or more targeted lifestyle interventions.

Future research may explore whether chronotype-tailored prevention strategies—such as personalized sleep, smoking cessation, and physical activity programs—can meaningfully reduce cardiovascular risk in individuals who naturally function later in the day.

Source

Cite this: Night Owls May Face Significantly Higher Cardiovascular Risk - Medscape - February 02, 2026.