Study links rotating night shift to higher risk of heart disease

Boston – Women who work rotating night shifts face a higher risk of heart disease, indicates a study of nurses from Brigham and Women’s Hospital and Harvard Medical School.

Using the Nurses’ Health Studies (1 and 2), researchers examined data from about 190,000 women who were tracked for more than 24 years. Rotating night shift work was characterized as at least three night shifts per month, in addition to day and evening shifts.

Researchers found that more than 10,000 cases of coronary heart disease were reported throughout the course of the study period. CHD cases included non-fatal heart attacks, stents and angioplasty.

Increasing years of rotating night shift work was connected to “a statistically significant but small absolute increase in CHD risk,” the study states. The connection between duration of shift work and CHD was stronger during the first period of follow-up, which researchers said may indicate declining risk after shift work ended. Researchers also found that the longer the length of time after quitting shift work, the lower the risk of CHD among nurses who were tracked every two to four years in the second study.

Previous research has found a link between shift work and CHD, metabolic disorders and cancer. “Social and biological rhythms” are interrupted during shift work, potentially increasing the risk of CHD, the release states.

“Further research is needed to explore whether the association is related to specific work hours and individual characteristics,” researchers wrote in the study.

The study was published April 26 in the Journal of the American Medical Association.