Circadian Rhythm, Sleep and a Link to Cancer

For many, working a night shift is a regular part of life. While most of the world operates on a 9-5 business model, a surprising number of businesses and services operate outside of “normal” hours. Hospitals need medical professionals, buildings need security and scores of drivers and workers need 24-hour gas stations and diners. Working during the night and sleeping during the day has become the norm in many professions.

Working an overnight shift can be mentally fatiguing, psychologically isolating and physically exhausting. Night shift work can even cause depressive episodes for some individuals. In a 2017 study, night shift work was partially linked to the development of cancer in some individuals. Parveen Bhatti, Ph.D., a researcher at the Fred Hutchinson Cancer Research Center in Seattle, studied the correlation between night shift work and the cellular repair process.

Night shift work has been under the microscope since 2001 when the first study conducted at Fred Hutchinson concluded that nurses working regular night shifts were in fact more likely to be diagnosed with cancer. These findings were repeated in 2007 by researchers at the International Agency for Research on Cancer. Bhatti took these findings and dug a little deeper. He aimed to understand what was happening to night shift workers at a molecular level.

By collecting urine samples from regular night shift employees, Bhatti was able to test whether melatonin suppression decreased the body’s ability to repair DNA. Melatonin regulates the body’s internal clock, known as circadian rhythms. Natural melatonin production is typically limited during the day and peaks after midnight. Exposure to light signals the body to produce less melatonin. This means that sleeping in a dark room overnight is essential to proper melatonin production. In his study, Bhatti discovered that the melatonin released overnight has a major impact on repairing DNA. Proper repair of DNA is essential for preventing mutations that can lead to cancer.

While melatonin is often sold as an over-the-counter sleep aid, Bhatti warns that such supplements are not an adequate replacement. Despite common misunderstanding, melatonin supplements are not sleep aids at all. The purpose of the supplement is to regulate sleep at night, but it does not work as a sleep aid during the day. Since it does not work as a sleep aid during the day, it is unlikely that melatonin supplements will have an impact on sleep patterns and, therefore, DNA repair.

While there are several more questions to be answered and studies to be done regarding Bhatti’s findings, it is imperative that night shift workers continue to look after their health. Until there is a way to combat melatonin’s role in DNA repair, night shift workers should continue to live (and sleep) in a health-conscious manner.

In addition to a healthy circadian rhythm, exercise and diet play a large role in preventing cancer. It is as important as ever for night shift employees to eat a balanced diet and incorporate exercise into their routine. Many night shift workers find it especially difficult to follow these guidelines as their schedule is vastly different to the majority of the world’s. Finding a 24-hour gym and meal prepping can help night shift workers keep a healthy lifestyle.

Along with sleep, diet and exercise, night shift workers should be mindful of other aspects of their health. This includes avoiding tobacco and limiting alcohol intake. While working the night shift may disrupt one’s sleep schedule, medical professionals state that getting at least eight hours of sleep each day can also improve their health.

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