Epigenetic markers of adverse lifestyle identified among evening and night shift workers in two UK population-based studies: Generation Scotland and Understanding Society

Epigenetic changes in the form of DNA methylation (DNAm) may act as biological markers of risk factors or adverse health states. In two cohort studies, Generation Scotland (GS) (n = 7,028) and Understanding Society (UKHLS) (n = 1,175), we evaluated associations between evening or night shift work and four lifestyle factors (body mass index, smoking, alcohol, education) through linear regression using both conventionally measured phenotypes and DNA methylation-based scores proxying the phenotypes. DNA methylation-based measures of biological ageing were also generated using six established “epigenetic clocks.” Meta-analysis of GS and UKHLS results was conducted using inverse-variance weighted fixed effects. Evening/night shift work was associated with higher BMI (0.79; 95%CI 0.02, 1.56; p = 0.04) and lower education ( − 0.18;  − 0.30,  − 0.07; p = 0.002). There was weak evidence of association between evening/night shift work and DNAm scores for smoking (0.06,  − 0.03, 0.15; p = 0.18) and education ( − 0.24;  − 0.49, 0.01; p = 0.06) in fully adjusted models (adjusted for age, sex, methylation principal components and phenotypic measures). Two of the epigenetic age measures demonstrated higher age acceleration among evening/night shift workers (0.80; 0.42, 1.18; p < 0.001 for GrimAge and 0.46; 0.00, 0.92; p = 0.05 for PhenoAge). In over 8,000 participants from two cohort studies, evening/night shift work was associated with both phenotypic and DNA methylation-based measures of higher BMI and lower education. DNAm predictors of smoking and ageing were also related to evening/night shift work. Epigenetic measures may provide insights into the health and lifestyle profiles of night shift workers.