Having unusual sleep patterns could increase cancer risk, according to new research printed in the journal Current Biology which found that disrupting the internal body rhythm of mice leads to decreased tumor suppression and other potentially harmful health issues.
In the study, experts from Erasmus University Medical Center Department of Genetics and the National Institute for Public Health and the Environment (RIVM) in the Netherlands found that chronic circadian rhythm disturbance (CRD) in mice made it more difficult for them to fight off cancer, and that they also put on weight, despite eating the same amount of food.
The researchers exposed breast-cancer prone rodents to chronic CRD by exposing them to an alternating light-dark cycle that delayed their body clock 12 hours each week for a period of one year. While the breast-cancer prone mice typically had tumors appear an after an average of 50 weeks, the sleep pattern disruptions caused them to appear eight weeks earlier.
The study also showed that the creatures were 20 percent heavier, even though they ate the same amount of food as normal mice, according to BBC News. This is said to provide the first-ever experimental proof that sleep disruption could increase the risk of breast cancer, and shows that internal desynchronization and unusual patterns of slumber could also be linked to obesity.
Night shift work could cause breast cancer five years earlier
While the study authors said that their findings demonstrate that women with a family risk of breast cancer should not work unusual hours, they also told the BBC that additional tests were needed to determine if disrupting the body clock also increases disease risk in humans.
The UK media outlet added that while it is difficult to interpret the findings and apply them to people, the authors estimated that the equivalent effect could be adding an extra 10 kilograms or 22 pounds of body weight in terms of weight, and developing breast cancer five years earlier in women who are at risk due to their family history.
“I consider this study to give the definitive experimental proof, in mouse models, that circadian [body clock] disruption can accelerate the development of breast cancer,” Dr. Michael Hastings from the UK’s Medical Research Council told BBC News. “The general public health message… is shift work, particularly rotational shift work is a stress and therefore it has consequences.”
“There are things people should be looking out for – pay more attention to your body weight, pay more attention to inspecting breasts, and employers should offer more in-work health checks,” he added. “If we’re going to do it, then let’s keep an eye on people and inform them.”
In a statement, the researchers noted that while the current study demonstrates that the chronic disruption of the biological clock and sleep patterns plays a role, epidemiological studies will be needed to fully determine the health risks of working the night shift. However, it will be another three to five years before the results of these studies will emerge, they added.
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