Researchers found that shiftwork was also associated with a 26% increase in coronary heart disease and a 20% increase in the risk of mortality from heart disease. 

Across all workers in the sample, the study found that shift workers had a 17% higher risk of a cardiovascular disease. However, the association only appears after five years of shiftwork and there was a 7.1% increase in risk for every five years’ exposure.

The study – a meta-analysis of 21 studies covering 173,010 participants – was published in the Scandinavian Journal of Work, Environment and Health.

It is thought that shiftwork alters the body’s internal clock, known as the circadian rhythm, which may affect metabolism and regulation of the nervous system.

Night-shift work causes work and sleep periods to become desynchronised, which can lead to reduced alertness, fatigue and sleep disturbances.

People who work shifts are more likely to be inactive, smoke, be overweight and have a poor diet compared to those who do not work shifts.

The paper calls on employers to undertake workplace health promotion initiatives and for more research on the relationship between lifestyle factors and shifts.

It is vital that employers implement appropriately designed patterns of shiftwork, produced in consultation with staff.

The HSE has produced good practice guidance on schedule design.