Women working night shifts are at increased risk for heart disease, heart attack and death, based on a recent analysis of the Nurses’ Health Studies.
Published in the Journal of the American Medical Association, this study looked at the cardiovascular impact of working overnights. Past studies have linked shift work to increased risk for heart disease but little is known about the long-term impact of night shifts on cardiovascular health.
Researchers analyzed data from the Nurses’ Health Studies, which followed nearly 190,000 healthy U.S. women for 24 years. Women were between the ages of 25 and 55 and completed questionnaires every few years during the study, providing information about their health and lifestyle.
A total of 115,535 women were included in the final analysis, all of who were free of heart disease at the start of the study and had a complete history of shift work.
During 24 years of follow-up, 9% of women developed or died from heart disease. Researchers found that women working at least three night shifts a month were up to 27% more likely to develop heart disease than those who did not.
However, women working night shifts for longer periods of time were at the higher end of the risk spectrum than those with less experience. For example, women working night shifts for ten or more years had 13–27% greater risk for heart disease than those with no night shifts, while women with less than five years of night shift experience had up to 10% increased risk.
Researchers also note that once nurses stop working night shifts, their increased risk for heart disease diminishes over time.
Based on findings, authors conclude that night shift work has a small but statistically significant increase in heart disease risk among female nurses. Additional research is needed to better understand the association between shift work and heart disease risk. However, findings suggest that night shift workers should take extra care to improve their heart health, especially if their work schedule tends to increase risk for heart disease.