Night shifts raise women's risk of heart disease, cancer
A new study published in the American Journal of Preventative Medicine suggests that women who have worked rotating night shifts for six years or longer were 19-23 percent more likely to die from cardiovascular disease and 11 percent more likely to die of any cause than those with little or no night-shift work. Women with 15 years or more on rotating night shifts also had a 25 percent increased risk of lung cancer death.
The team from Brigham and Women’s Hospital and Harvard Medical School in Boston used data from the Nurses’ Health Study, and included nearly 75,000 female registered nurses in their analysis. The researchers followed the women from 1988 to 2010, at which point 14,181 women had died. The team then looked at the women’s weight, diets, lifestyles and other factors as well as their causes of death.
Among women who had done 15 or more years of night shifts at least three nights per month, there were 1,430 deaths, 364 from cardiovascular disease and 506 from cancers (150 from lung cancer). The results held even after they were adjusted for weight, smoking and other factors that might explain the link between shift work and disease.
The author’s note that the body’s circadian clock system is believed to influence many aspects of health, and the sleep-regulating hormone melatonin is thought to have antitumor effects, so perhaps night shift hours could disrupt melatonin and disturb systems that control heart rate, inflammation and metabolism of blood sugar and fats.