Sina Kianersi, PhD, is a research fellow in medicine at Brigham and Women’s Hospital.

Sina Kianersi, PhD

Staying Up Late Associated With CVD Risk Through Worse LE8 Scores, With Sina Kianersi, PhD

Individuals with an evening chronotype, or “night owls,” may be at greater risk of 

; however, a significant percentage of contributing factors are modifiable.

During the 14-year trial, participants with a “definitely evening” chronotype – defined as having a late-night bedtime such as 2 a.m. and peak activity later in the day – were associated with a 79% higher prevalence of overall poor Life’s Essential 8 (LE8) scores. By the end of the trial, investigators had recorded 17,584 incident cardiovascular disease events.

“The encouraging part of our findings, however, is that roughly 75% of that difference seemed to be explained by modifiable factors such as sleep, physical activity, smoking, weight, blood pressure, cholesterol, and blood sugar,” Sina Kianersi, PhD, research fellow in medicine at Brigham and Women’s Hospital, told 

Kianersi and colleagues conducted a prospective study using UK Biobank assessment center visits as the baseline. A total of 502,128 patients were initially included in the dataset – of these, 6172 were excluded due to missing chronotype information, 18,292 were excluded due to a history of myocardial infarction (MI) or 

 at baseline, and 154,887 were excluded due to incomplete data on ≥1 lifestyle behaviors or factors among LE8. A total of 322,777 patients were ultimately enrolled and followed up over a duration of 14 years.

Chronotype was self-reported at baseline visit using a single question from the Morningness-Eveningness Questionnaire. This question’s correlation coefficient with the full questionnaire score surpasses 0.72. The LE8 framework is composed of 4 health behaviors – diet, physical activity, nicotine exposure, and sleep health – and 4 health factors – body weight, blood lipids, blood glucose, and blood pressure. Each component has a scoring algorithm from 0 to 100, with higher scores indicating better cardiovascular health. Diet, physical activity, sleep duration, and nicotine exposure were self-reported, while weight, blood lipids, blood glucose, and blood pressure were measured directly.

The mean age of the study population was 57 years (+/- standard deviation [SD] 8). Roughly 58% of participants had a family history of cardiovascular disease. The majority of participants (67%) had an “intermediate” chronotype, with 8% reporting a "definitely evening" chronotype. Compared with the “intermediate” chronotype, those with a “definitely evening” chronotype were younger, were more frequently engaged in shift work (12% vs 9%), more frequently held college degrees (43% vs 37%), and had a lower overall LE8 score (65 vs 68). In a descriptive analysis, “definitely evening” participants had notably poorer scores in 7 of 8 components compared to the “intermediate” participants.

Ultimately, after a median follow-up of 13.8 years (interquartile range [IQR], 1.6), 17,584 incident cardiovascular disease cases (MI = 11,091; stroke = 7214) were documented among all participants. Compared with the “intermediate” chronotype, those with a “definitely evening” chronotype had a 16% higher risk of cardiovascular disease (HR, 1.16; 95% CI, 1.1-1.22), while those reporting “definitely morning” chronotypes were not at an increased risk (HR, 1.03; 95% CI, 0.99-1.07). After adjusting for the 8 LE8 components, associations attenuated; however, no direct effect of evening chronotype on cardiovascular disease was observed, as the natural indirect effect, representing the effect mediated by the overall LE8 score, was 1.11 (95% CI, 1.09-1.13). This indicated that 75% of the association between chronotype and incident cardiovascular disease was mediated through these scores.

Ultimately, although evening chronotype was directly associated with a poorer score in LE8, this renders it reversible through alterations to diet, physical activity, and nicotine exposure, among other factors. Kianersi and colleagues emphasized that chronotype had no direct influence on cardiovascular disease.

“One of the limitations of the study is that we followed the cohort for about 14 years, and the risk is for that specific number of years,” Kianersi said. “The risk might be different for shorter or longer study periods – it might change if we follow participants for a longer time, as we had in our previous studies.”

Editor’s Note: Kianersi reports no relevant disclosures.

American Heart Association. Being a night owl may increase your heart risk. 

. January 28, 2026. Accessed January 29, 2026. 

https://www.eurekalert.org/news-releases/1113759

Kianersi S, Potts KS, Wang H, et al. Chronotype, life’s essential 8, and risk of cardiovascular disease: A prospective cohort study in UK Biobank. Journal of the American Heart Association. Published online January 28, 2026. 

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Kianersi discusses how, although evening chronotype can be associated indirectly with increased CVD risk, this can be mediated via Life’s Essential 8 scores.

Sina Kianersi, PhD

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