A large UK Biobank study has quantified the cardiovascular cost of permanent night work — and how much of it might be avoidable. Published in the Journal of Global Health, the study followed 131,844 employed adults with no cardiovascular disease at the start, for a median of 13.78 years. Over that time, 39,115 people (29.7%) developed cardiovascular disease and 5,474 (4.2%) died.
Permanent night shift workers carried a clearly higher risk. Compared with day workers, those on usual or permanent night shifts had:
- 24% higher risk of cardiovascular disease (hazard ratio 1.24, 95% CI: 1.18-1.31)
- 23% higher risk of death from any cause (HR 1.23, 95% CI: 1.07-1.41)
- 31% higher risk of atrial fibrillation (HR 1.31, 95% CI: 1.13-1.51)
- 29% higher risk of heart attack (HR 1.29, 95% CI: 1.09-1.51)
Cardiovascular death specifically was not significantly elevated.
The study's real contribution is showing how much of that risk runs through lifestyle. Researchers scored participants on the American Heart Association's Life's Essential 8 — a composite of diet, physical activity, nicotine exposure, sleep, weight, blood pressure, lipids, and blood glucose. That score explained 39.2% of the elevated CVD risk among night workers, 33.1% of the mortality risk, and 40.8% of the heart attack risk.
The more striking number is what a counterfactual analysis suggested could be prevented. If night shift workers achieved the same cardiovascular health scores as day workers, the model estimated that 35.1% of their excess cardiovascular events and 30.2% of their excess deaths could be avoided — without changing their work schedule at all.
What this study cannot show is that improving those eight lifestyle factors would actually deliver that reduction in the real world; the estimate comes from statistical modeling of observational data, not a trial where night workers were assigned to a lifestyle program. Night work itself may also carry effects — on circadian biology, for instance — that a lifestyle score cannot fully capture or correct for.
Bottom line. Permanent night shift work was associated with meaningfully higher cardiovascular risk in this cohort, but a substantial share of that risk tracked with modifiable factors like diet, activity, sleep, and blood pressure — factors within reach even for people who cannot change their schedule.
Medical note. This article is for general educational purposes and should not be considered personal medical advice.