The findings, reported in the American Journal of Preventive Medicine, indicate women working rotating night shifts for five or more years are more likely to die of cardiovascular disease and those working such schedules for 15 or more years have a modest increase in lung cancer mortality.
 

The research, led by Harvard University, echoes past studies that have found rotating night shift work disrupts natural wake-sleep cycles and has a serious, negative effect on health and longevity.

In 2007 the World Health Organization classified night shift work as a probable carcinogen.

The latest findings are based on reviews of information gathered from a long-running study of almost 75,000 registered U.S. nurses, called the Nurses' Health Study.
 

The results showed premature death rates from all causes to be 11 percent higher for women working rotating night shifts. Cardiovascular deaths were up to 23 percent higher, while lung cancer deaths in those who worked night shifts for 15 or more years were up 25 percent.
 

"These results add to prior evidence of a potentially detrimental relation of rotating night shift work and health and longevity,” said researcher Eva S. Schernhammer, M.D., who added that the study "is one of the largest prospective cohort studies worldwide with a high proportion of rotating night shift workers and long follow-up time. A single occupation [nursing] provides more internal validity than a range of different occupational groups, where the association between shift work and disease outcomes could be confounded by occupational differences."