Chronotype Differences in Energy Intake, Cardiometabolic Risk Parameters, Cancer, and Depression: A Systematic Review with Meta-Analysis of Observational Studies.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational studies (37 cross-sectional, 2 prospective cohort)
PubMed 34549270 · doi:10.1093/advances/nmab115
What was done
Authors conducted a systematic review and meta-analysis across MEDLINE, Embase, Scopus, Web of Science, and Cochrane Database evaluating the association between chronotype (morning versus evening preference), energy intake, and health indicators. The review included 39 observational studies (37 cross-sectional, 2 prospective cohort) comprising 377,797 participants.
What was found
Pooled analyses of cross-sectional studies showed that evening chronotypes had significantly higher (P < 0.001) levels of blood glucose (mean difference [MD]: 7.82; 95% CI: 3.18, 12.45), glycated hemoglobin (MD: 7.64; 95% CI: 3.08, 12.21), LDL cholesterol (MD: 13.69; 95% CI: 6.84, 20.54), and triglycerides (MD: 12.62; 95% CI: 0.90, 24.35) compared to morning chronotypes. Evening preference was also associated with increased risk of diabetes (OR: 1.30; 95% CI: 1.20, 1.41), cancer (OR: 1.18; 95% CI: 1.08, 1.30), and depression (OR: 1.86; 95% CI: 1.20, 2.88). No significant differences were found for energy intake, anthropometric parameters, blood pressure, insulin, total cholesterol, HDL cholesterol, or hypertension risk.
Why it matters
This review synthesizes large-scale observational data linking an evening chronotype to adverse cardiometabolic profiles and elevated odds of chronic physical and psychiatric conditions.
Limits
The vast majority of included studies (37 of 39) were cross-sectional, precluding causal inference or establishment of temporal sequence. The abstract does not specify the units of measurement for biomarker differences or how chronotypes were assessed across disparate studies.
Cited by
- supports Having an evening chronotype (being a night owl) is associated with increased health risks compared to having a morning chronotype.