Social Jetlag, Chronotype, and Cardiometabolic Risk.
Level 4 - case-series / case-control
Cross-sectional observational study evaluating associations between circadian misalignment and metabolic markers.
PubMed 26580236 · doi:10.1210/jc.2015-2923
What was done
Researchers evaluated 447 healthy, midlife adults (mean age 42.7 years, range 30–54; 53% female; 83% white) who worked part- or full-time day shifts. Chronotype was evaluated using the Composite Scale of Morningness. Social jetlag was measured via wrist actigraphy as the difference in minutes between sleep midpoints on workdays versus non-workdays. Multiple regression models analyzed associations between social jetlag, chronotype, and cardiometabolic risk markers while adjusting for subjective sleep quality, actigraphy-measured sleep parameters, depressive symptoms, and health behaviors.
What was found
Social jetlag was significantly associated with lower high-density lipoprotein (HDL) cholesterol, higher triglycerides, higher fasting plasma insulin, greater insulin resistance, and higher adiposity (all P < .05) after adjusting for sleep quality, sleep characteristics, depressive symptoms, and health behaviors. Evening chronotype was independently associated with lower HDL cholesterol after covariate adjustment. Exact numerical effect estimates were not reported in the abstract.
Why it matters
These findings suggest that routine day-to-day circadian misalignment from discrepancies between biological sleep timing and social schedules is linked to adverse metabolic profiles independently of total sleep duration, sleep quality, and lifestyle factors.
Limits
The study design was cross-sectional, precluding causal inferences. The cohort consisted primarily of healthy, white, midlife adults working day shifts, limiting generalizability to shift workers, diverse racial or ethnic groups, and clinical populations. Numerical effect sizes and confidence intervals were not reported in the abstract.
Cited by
- supports Evening chronotypes who do not sleep according to their circadian preference have higher C-reactive protein, poorer HbA1c control, and higher obesity rates.