Do the Long-Term Cardiometabolic Effects of Night Shift Work Differ Between Men and Women? A 17-Year Cohort Study of the U.S. Workforce

Shift work, particularly night shifts, has been linked to adverse health outcomes, including disruptions in circadian rhythms that may contribute to metabolic disorders. However, sex-related differences in the impact of night shift work on cardiometabolic health remain understudied. This study sought to examine the relationship between night shift work and cardiometabolic health in young adults, identifying potential sex-related differences. In this prospective cohort study, a total of 3201 participants (mean age 22.08 years, 59.9% women) were analyzed over a 17-year period. Relative risks (RR) with 95% confidence intervals (CI) were calculated to evaluate the impact of night shift work on cardiometabolic health outcomes, including obesity, hyperlipidemia, hypertension, type 2 diabetes, and metabolic syndrome. At Wave V, 74.7% of participants were diagnosed with overweight/obesity, 51.8% with abdominal obesity, 15.5% with hyperlipidemia, 29.1% with hypertension, 8.3% with type 2 diabetes, and 20.9% with metabolic syndrome. Night shift work was associated with an increased risk of obesity and abdominal obesity in women (RR=1.99, 95% CI: 1.08 to 3.65, and RR=1.60, 95% CI: 1.07 to 2.56, respectively), but not in men. Women also showed an elevated risk of diabetes (RR=2.69, 95% CI: 1.49 to 4.86), whereas no significant relationship was identified in men. Night shift work was not significantly associated with hypertension and metabolic syndrome in either men or women. Women working night shifts may benefit from targeted interventions for cardiometabolic health, particularly in managing weight and preventing diabetes, while men did not exhibit similar associations.