Metabolic biomarkers and cardiometabolic risk among night shift workers: evidence from night shift workers in Europe

Circadian disruption resulting from night shift work has been associated with cardiometabolic diseases, but the underlying biological pathways remain insufficiently understood. We analyzed data from the EPHOR-NIGHT cohort, including questionnaires, clinical assessments [body mass index (BMI), blood pressure (BP), waist/hip circumference], and plasma metabolites in blood samples (N = 860; day shift workers n = 362, night shift workers = 498) from Sweden, Spain, and Denmark. We applied multivariable linear regression to examine differences in cardiometabolic risk factors and metabolite levels between shift workers and examined associations between metabolites and cardiometabolic risk factors. Night shift work was associated with higher mean systolic BP (β = 1.89, 95%CI 0.00, 3.79 mmHg), higher mean BMI (β = 1.14, 95%CI 0.44, 1.84 kg/m2), and higher odds of hypertension (OR = 1.38, 95%CI 1.00, 1.89) and overweight/obesity (OR = 1.37, 95%CI 1.02, 1.82), compared to day shift work. Associations were stronger among women in sex-stratified analyses. Night shift workers had metabolic alterations, with lower fractions of polyunsaturated fatty acids, higher fractions of mono-unsaturated and saturated fatty acids, and higher levels of amino acids isoleucine, valine, and phenylalanine. These changes remained after multiple adjustments, including diet. Effects were more pronounced for those working more consecutive night shifts, more night shifts per week, and for permanent night schedules versus rotating shifts. The night shift-related metabolites were associated with higher BMI and higher blood pressure. Night shift work was associated with specific metabolic alterations linked to increased cardiometabolic risk. Our results suggest that reducing night shift intensity and consecutive nights may help mitigate these adverse effects.