Nursing is one of the professions in which night shifts are required. While this makes sense in that patients need care 24 hours a day, working night shifts takes a toll on nurses. There's good evidence that working night shifts on a regular basis or working rotating shifts increases the risk of heart disease.
Sleep, Heart Disease and Cancer
The long-running Nurse's Health Study looked at the issue of rotating shifts in 2015. More than 74,000 registered nurses provided data regarding their history of shift work and multiple health indicators like heart disease and cancer mortality. The researchers found that women who had worked at least five years of rotating night shifts had an increased risk of both all-cause mortality and death from heart disease. Women who worked at least 15 years of rotating night shifts had a slight increase in death from lung cancer.
Sleep and Heart Disease Risk
A more recent study confirmed the original findings. For this study, researchers defined heart disease as chest pain, medically confirmed angina, a heart attack or blocked arteries that required surgery, stents or similar treatment. In this study, younger women who had worked night shifts for 10 years or longer were found to have a 27 percent higher risk of heart disease compared to those who had not worked night shifts. The increased risk of heart disease occurred even in women who had no known heart disease risk factors, such as smoking, high blood pressure or diabetes. (Be sure to read our blog on how to learn the warnings signs of a heart attack)
Night Shifts and Other Health Indicators
Night shifts also affect women's health in other ways. Nurses who worked night shift were more likely to smoke and to use painkillers. Shift work increased the risk of weight gain – the longer a woman worked night shift, the more weight she gained.
Researchers theorized that shift work disrupted biological processes such as the circadian rhythm. Sleep is the time when the body repairs cells and tissues, and restores balance to many important body processes. Disrupted or inadequate sleep alters levels of melatonin, the hormone that governs the sleep-wake cycle. It also increases secretion of the stress hormone cortisol. Sleep deprivation also alters the balance of many biological functions, which can lead to inflammation, changes in fat and sugar metabolism and diminished immune function.
People who work night shifts must take extra efforts to ensure adequate sleep – blackout blinds; sound-proofing; a cool, dark room and minimal use of caffeine and alcohol. The use of sleeping medications can make the problem worse and should be avoided. The good news? Once a woman stops working night shifts, the body gradually normalizes and the increased risk of heart disease drops.
- Céline Vetter, PhD; Elizabeth E. Devore, ScD; Lani R. Wegrzyn, ScD; et al. Association Between Rotating Night Shift Work and Risk of Coronary Heart Disease Among Women. JAMA. 2016;315(16):1726-1734. doi:10.1001/jama.2016.4454. https://jamanetwork.com/journals/jama/fullarticle/2516715
- Eva S. Schernhammer, MD, DrPH; et.al. Total and Cause-Specific Mortality of U.S. Nurses Working Rotating Night Shifts. AJPM. 2015; 48: 241-252. doi: 10.1016/j.amepre.2014.10.018 http://www.ajpmonline.org/article/S0749-3797%2814%2900623-0/fulltext