Long-term night work carries growing cardiovascular risk; consider changing shifts early when feasible
Night workers had about 13% more cardiovascular disease and 27% more cardiovascular deaths. Each additional five years of night work was associated with another 7% increase in disease. Consider the cumulative years when weighing a transfer. Cancer evidence is much weaker than common claims suggest.
What it takes
A transfer or new job may mean lower pay and lost night-shift allowances, plus job-search time and a difficult decision. Considering this before accepting a job costs nothing.
What you may gain
A meta-analysis of 23 observational cohorts found RR 1.13 for cardiovascular events (95% CI 1.10–1.16), about 13% higher, and 1.27 for cardiovascular mortality (1.18–1.36), about 27% higher. Each additional 5 years was associated with RR 1.07 for cardiovascular incidence (1.04–1.09), about 7% higher, and 1.05 for mortality (1.03–1.06), about 5% higher. Specific estimates were 1.22 for coronary disease incidence (1.16–1.28), 1.22 for coronary mortality (1.10–1.36), 1.39 for ischemic-heart-disease mortality (1.06–1.84), and 1.49 for stroke mortality (1.04–2.12): approximately 22%, 22%, 39%, and 49% higher risks, respectively. Stroke incidence was not significantly increased: 1.06 (0.95–1.18).
Context & considerations
Night workers differ in smoking, weight and income, and observational adjustment is incomplete. A meta-analysis of 12 studies with 12,132 breast-cancer cases found RR 1.05 for ever working nights (0.96–1.14). At 20 years of night work, RR was 1.25 (1.01–1.55), but this lost significance in influence analysis and approached 1 after adjustment for possible publication bias; the authors considered the association far from established. A Chinese male cohort followed for 16.1 years with 8,202 cancers found no association with total or most common cancers; only pancreatic cancer at 11–20 cumulative years was elevated (HR 1.59, 1.09–2.31). This entry therefore weighs cardiovascular risk, not cancer. Leaving night work is an individual decision, not a universal requirement. First address smoking, blood pressure and lipids, and recovery sleep. Two possible measures are restricting meals to daytime and shifting the body clock through bright light at night plus strict daytime darkness. The source describes the latter as the only approach demonstrated to shift the clock: six night shifts under ordinary indoor light produced no shift, whereas 7,000–12,000 lux with near-total daytime darkness reversed it within four days. Bright light at night, strict darkness for daytime sleep, and sunglasses blocking morning light on the journey home all matter; the source warns that omitting the last can undo the effort. Trials measured metabolic markers and sleep, not whether cardiovascular risk fell. Returning to daytime life on days off can shift the clock back. Doses, original figures, other sources and an explanation of biological time are in the body clock and night work.
Research & references
Xi J, Ma W, Tao Y, et al. (2025). Association between night shift work and cardiovascular disease: a systematic review and dose-response meta-analysis. Frontiers in Public Health. https://doi.org/10.3389/fpubh.2025.1668848 ; Esposito G, Bravi F, Santucci C, et al. (2025). Night shift work and breast cancer risk in healthcare workers: a systematic review and meta-analysis. Occupational Medicine. https://doi.org/10.1093/occmed/kqaf040 ; Shen QM, Li ZY, Tan YT, et al. (2026). Night shift work and risk of total and site-specific cancer: results from a prospective cohort study among Chinese men. Scandinavian Journal of Work, Environment & Health. https://doi.org/10.5271/sjweh.4290 ; Czeisler CA, Johnson MP, Duffy JF, et al. (1990). Exposure to bright light and darkness to treat physiologic maladaptation to night work. New England Journal of Medicine, 322(18), 1253-1259. https://doi.org/10.1056/NEJM199005033221801