Middle-aged and older adults who are naturally more active in the evenings, known as night owls, have poorer cardiovascular health compared to their morning-active peers, with women showing particularly strong associations, according to research published in the Journal of the American Heart Association. The study analyzed data from over 300,000 UK Biobank participants with an average age of 57, finding that self-reported "definitely evening people" had a 79% higher prevalence of poor cardiovascular health scores and a 16% increased risk of heart attack or stroke over approximately 14 years compared to intermediate chronotypes.
Cardiovascular health was measured using the American Heart Association's Life's Essential 8 metrics, which assess diet, physical activity, smoking status, sleep quality, weight, cholesterol, blood sugar, and blood pressure. Researchers found that much of the elevated risk among evening chronotypes stemmed from unhealthy behaviors, particularly nicotine use and inadequate sleep. Lead author Sina Kianersi of Brigham and Women's Hospital and Harvard Medical School noted that "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."
The study offers a crucial insight: these risks appear largely modifiable. Kristen Knutson, who chaired the 2025 American Heart Association statement on circadian health, emphasized that "evening types have options to improve their cardiovascular health" since the higher risks are "partly due to modifiable behaviors." The research suggests that targeted interventions considering individual chronotype could help night owls improve lifestyle behaviors. More information about cardiovascular health metrics is available at https://www.heart.org/en/healthy-living/healthy-lifestyle/my-life-check--lifes-essential-8.
While the study has limitations—including a predominantly white, healthier participant pool and reliance on self-reported chronotype data—the findings highlight the importance of circadian alignment for cardiovascular wellbeing. The American Heart Association's scientific statement suggests that "some medications or therapies work best when they align with a specific time of relevant circadian rhythms," indicating potential for chronotype-aware healthcare approaches. The full manuscript is accessible at https://www.ahajournals.org/doi/10.1161/JAHA.125.034567.
