Body-Clock Testing to Mitigate Health Risks of Night Work: A Prospective Cohort Study Protocol on Chronomedicine for Shift Workers

Night-shift work is essential to modern industries but disrupts circadian rhythms, increasing risks of cardiometabolic disease, cancer, and mental health conditions. The International Agency for Research on Cancer (IARC) classifies “night-shift work involving circadian disruption” as “probably carcinogenic to humans” (Group 2A). Advances in chronobiology now enable precise estimation of internal circadian phase using transcriptomic, metabolomic, and wearable-based assessments. This protocol outlines a 24-month prospective cohort study evaluating the association between circadian misalignment and adverse health outcomes among 500 night-shift workers and 250 day-shift controls. Circadian phase will be assessed using multi-modal biomarkers and machine-learning models. Outcomes include metabolic, cardiovascular, inflammatory, and mental-health indicators. Mixed-effects regression models will examine longitudinal associations while adjusting for lifestyle and occupational covariates. The study aims to determine the feasibility of body-clock testing for personalized health interventions and improved shift-schedule design. Findings may inform occupational health policies and contribute to circadian-based preventive strategies for shift-dependent sectors.