Later chronotype was associated with a less favourable subclinical adiposity-atherogenic profile independently of perceived sleep quality in adults without previously diagnosed chronic disease.
Key Findings
Results
Higher MEQ score (greater morningness) was independently associated with lower log-transformed Visceral Adiposity Index (log[VAI]).
B = -0.0096; 95% CI, -0.0159 to -0.0033; β = -0.190; p = 0.003
Association remained independent after adjusting for age, sex, education, physical activity, and PSQI score
Multivariable linear models used heteroscedasticity-consistent type 3 (HC3) robust standard errors
Sample included 282 adults without previously diagnosed chronic disease or regular medication use
Results
Higher MEQ score (greater morningness) was independently associated with lower Atherogenic Index of Plasma (AIP).
B = -0.0035; 95% CI, -0.0063 to -0.0008; β = -0.160; p = 0.011
BMI was additionally included as a covariate in the AIP model alongside age, sex, education, physical activity, and PSQI
Association was significant after false-discovery-rate (FDR) correction
Results
Pittsburgh Sleep Quality Index (PSQI) score was not independently associated with either log(VAI) or AIP.
PSQI was included as a covariate in all multivariable models
51.8% of participants had poor sleep quality as assessed by PSQI
Chronotype and sleep quality were treated as related but non-identical dimensions of sleep health
The finding suggests that chronotype effects on cardiometabolic indices are independent of perceived sleep quality
Results
Sex × MEQ interaction terms were nominally significant with stronger estimates in women, but did not survive FDR correction.
50.4% of participants were women
Interaction terms were described as 'nominally significant' but failed to survive false-discovery-rate correction
The authors describe the sex-specific pattern as 'hypothesis-generating'
The study was described as 'sex-aware' and specifically examined whether associations differed by sex
Results
Associations between chronotype and cardiometabolic indices persisted after excluding diabetes-range glycaemia but attenuated in strictly normoglycaemic participants.
Glycaemic sensitivity analyses were performed as a robustness check
Associations persisted after excluding participants with diabetes-range glycaemia
Attenuation was observed when analysis was restricted to strictly normoglycaemic participants
This finding suggests glycaemic status may partially mediate or modify the chronotype-adiposity relationship
Methods
The study sample was predominantly young, with a notable proportion classified as evening type.
Median age was 28.0 years
25.9% were classified as evening type based on MEQ
282 adults were included, all without previously diagnosed chronic disease or regular medication use
This was a single-centre cross-sectional study
What This Means
This research suggests that people who are naturally inclined to stay up late and wake up later (so-called 'evening chronotypes' or 'night owls') tend to have worse markers of hidden fat accumulation around their organs and more harmful blood lipid profiles, even when they do not yet have any diagnosed chronic disease. This was true regardless of whether participants reported poor sleep quality, meaning the time-of-day preference itself — not just how well someone sleeps — appears to matter for these early cardiovascular risk indicators. The study measured these associations using two composite scores calculated from standard clinical measurements: the Visceral Adiposity Index and the Atherogenic Index of Plasma.
The study involved 282 relatively young adults (median age 28 years) in a single medical centre, and about one in four was classified as an evening type. Roughly half reported poor sleep quality. Statistical models accounted for age, sex, education level, physical activity, and sleep quality to isolate the specific contribution of chronotype. The associations appeared somewhat stronger in women than in men, but this sex difference was not statistically robust enough to be considered a confirmed finding — the authors describe it as a direction for future research rather than a firm conclusion.
This research suggests that an individual's internal body clock timing — independent of sleep quality — may contribute to early, subclinical cardiovascular risk even in otherwise healthy young adults. However, because this was a cross-sectional study (a snapshot in time), it cannot establish that being a night owl causes these changes. Future studies tracking people over time and using objective measurements of sleep timing, diet timing, hormones, and physical activity would be needed to understand the mechanisms involved and whether shifting sleep timing could reduce these risks.
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Lule K, Şahin S, Otay Lule N, Savcilioglu M, Yildiz H. (2026). Chronotype and Atherogenic-Adiposity Indices in Adults Without Previously Diagnosed Chronic Disease: A Sex-Aware Cross-Sectional Study.. Medicina (Kaunas, Lithuania). https://doi.org/10.3390/medicina62081472