Middle-aged and older adults who are naturally more active in the evenings exhibit poorer cardiovascular health compared to their morning-active peers, with women showing particularly pronounced effects. A study published in the Journal of the American Heart Association analyzed data from over 300,000 UK Biobank participants, finding that self-identified "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.
The research utilized the American Heart Association's Life's Essential 8 metrics to assess cardiovascular health, evaluating factors including diet, physical activity, smoking status, sleep quality, weight, cholesterol, blood sugar, and blood pressure. While about 24% of participants identified as "definitely morning people" and 67% as intermediate chronotypes, approximately 8% were classified as evening chronotypes. Lead author Sina Kianersi noted that evening people often experience circadian misalignment, where their internal body clock conflicts with natural light cycles and daily schedules, potentially leading to unhealthy behaviors.
Key findings indicate that much of the elevated cardiovascular risk among night owls stems from modifiable factors, particularly nicotine use and inadequate sleep. Kristen Knutson, who chaired the 2025 American Heart Association statement on circadian health, emphasized that evening types aren't inherently less healthy but face specific challenges requiring targeted lifestyle interventions. The study suggests that chronotype should be considered when timing medical interventions, as some treatments work best when aligned with individual circadian rhythms.
Researchers highlight that helping night owls improve lifestyle habits could substantially reduce their cardiovascular disease risk. The American Heart Association provides resources for assessing cardiovascular health through initiatives like the Life's Essential 8 My Life Check Calculator. Study limitations include the predominantly white and generally healthier UK Biobank population, which may affect generalizability, and the reliance on self-reported chronotype data collected at a single time point.
