More and more products and services are now offered day and night, thanks to the presence of employees around the clock. As a result, night shifts are becoming an increasingly common phenomenon. However, the prevalence of night work is causing researchers to sound the alarm. Evidence of the harmful effects of such working hours has been accumulating in recent years. Night work is now associated with an increased risk of cardiovascular disease, depression, and various forms of cancer. One study even suggested that the damage attributed to a night shift was greater than that associated with smoking twenty cigarettes a day.
Unfortunately, the results of a recently published study point in the same direction as previous studies on the subject. The research aimed to assess a night shift's impact on breast cancer incidence in women. Data from over 10,000 women were analyzed. The researchers concluded that a woman working night shifts has up to a 50% greater risk of developing breast cancer than a woman working day shifts—a substantial hike.
Several reasons have been identified. In particular, it is thought that exposure to artificial lighting may stimulate the production of estrogen, a female hormone implicated in breast cancer. A second explanation involves melatonin, another hormone normally produced in greater quantities at night, which helps regulate the sleep cycle. Researchers believe that women with high levels of melatonin in the morning may be at less risk of breast cancer, which would not be true for night workers.