BACKGROUND: Individuals with an evening chronotype often experience circadian misalignment, which may disrupt health behaviors and cardiometabolic functions.
METHODS: We conducted a prospective study in 322 777 UK Biobank participants aged 39 to 74 years free of known cardiovascular disease (CVD). Chronotype was self-reported using a single representative question. The Life's Essential 8 (LE8) score was calculated from 8 CVD risk factors and ranged from 0 to 100 with higher scores indicating better cardiovascular health. Incident CVD was defined as first myocardial infarction or stroke. Cox proportional hazards models estimated the association between chronotype and CVD risk, adjusted for sociodemographics, shift work, and family history of CVD. We evaluated the role of LE8 in the chronotype-CVD association by decomposing the total effect into natural direct effect (independent of LE8) and natural indirect effect (mediated by LE8).
RESULTS: Participants with a "definite evening" chronotype were associated with 79% higher prevalence of an overall poor LE8 score (<50 points) compared with "intermediate" type (95% CI, 1.72-1.85). Over a median 13.8 years of follow-up, there were 17 584 incident CVD events (11 091 myocardial infarction; 7214 stroke). The hazard ratio (HR) for total CVD was 1.03 (95% CI, 0.998-1.07) for the "definite morning" and 1.16 (95% CI, 1.10-1.22) for "definite evening" compared with "intermediate" chronotype (-trend: 0.10). LE8 explained 75% of the association between evening chronotype and CVD (natural indirect effect comparing "definite evening" with "intermediate": HR, 1.11 [95% CI, 1.09-1.13]). P
CONCLUSIONS: Our findings suggest that individuals with an evening chronotype may particularly benefit from interventions targeting CVD risk factors.
Circadian Biology