(HealthDay News) — Women who work rotating night shifts may face a slightly increased risk of coronary heart disease (CHD), according to a report published in the Journal of the American Medical Association.
Celine Vetter, PhD, instructor in medicine at Brigham and Women’s Hospital in Boston, and colleagues collected data on 189 158 women who took part in the Nurses’ Health Study I and II. All of the women in the study reported their lifetime exposure to rotating night shift work.
The researchers used medical records and death certificates to confirm any self-reported nonfatal myocardial infarction or CHD death. The women also completed questionnaires about their known risk factors for CHD every 2 to 4 years throughout the 24-year study period.
Over that time, 10 822 women developed incident CHD. To isolate the effect of shift work, the investigators took into account a number of known risk factors for CHD, such as smoking, poor diet, lack of physical activity, and weight.
Even after controlling for these risk factors, a modest increase in the risk for CHD was seen with longer duration of rotating night shift work. The increased risk ranged from 15% to 18% when compared with women who did not work rotating night shifts.
However, the more time that elapsed after quitting such night shift work, the lower the risk for CHD. This “further supports the hypothesis that the risk of coronary heart disease associated with shift work might wane over time when women stopped working [such] shifts. This is a new finding,” Dr Vetter told HealthDay.
“Although only a small number of women had an increased risk, and even though the absolute risk associated with shift work is small, and the contribution of shift work to coronary heart disease is modest, this is a modifiable factor, and changing schedules might help prevent coronary heart disease.”