Study Finds Sleep Disorder Increases Risks Of Breast Cancer, Obesity

A new study found shifting sleep patterns has been associated with a high risk of getting cancer. Researchers from Erasmus University Medical Center found that irregular sleep has increased the risk of acquiring the disease and weight gain through frequent shift of poor sleeping habits.

The study, issued on Monday in Current Biology, shows the result of the damaging impact of shifting sleep patterns on health. Researchers from Netherlands studied female mice with a genetic predisposition to breast cancer, comparable to women who carry a BRCA or a Li-Fraumeni p53 mutation, defined as a hereditary cancer predisposition syndrome.

The scientists delayed the body clock of mice by 12 hours every week for a year. The researchers said that the mice were expected to develop breast cancer in 50 weeks, but with regular disruption to their sleeping patterns, the tumours appeared eight weeks earlier than expected. The mice, subjected to the alternative light-dark cycles, also gained about 20 percent more weight than those that were not.

The mice were subjected to disruptions on human-relevant circadian rhythm. Circadian rhythm is described as the "internal body clock" that regulates the 24-hour cycle of biological processes in the body, according to the Cleveland Clinic. The disruptions provided early causal evidence that weekly alternating light-dark cycles, or the sleep cycle of the subject, may rush certain health risks.

In the mouse study, the scientists show that the lack of sunlight or low Vitamin D levels are not the primary factors in the development of breast cancer and weight gain of the mice. The senior study author, Bert van der Horst, said that they found the circadian rhythm disruption is the causal factor associated with the illness.

"The conclusion is that chronic changes in light schedules are a driving factor for breast cancer development, weight gain, and other metabolic problems," van der Horst said.

However, researchers stated that the conducted study needs further variables to confirm that sleep pattern disruption is correlated to or the cause of cancer to humans. “The experimental conditions of many of these animal studies were far from the reality of human shift workers,” the study indicated.

In the past, studies in people have suggested that women who worked long-term on night shifts had doubled the risk of breast cancer compared with people who had never worked night shifts, including flight attendants, according to Dr Jane Green, clinical epidemiologist at Oxford University.

Additionally, Till Roenneberg, head of Human Chronobiology at Ludwig-Maximilian University in Germany, stated that the recent study is "in line with what has been found in epidemiological studies in humans, and now provides strong causal evidence for circadian disruption as a carcinogenic factor," after analysing the chronological disturbances made into the sleep patterns of the mice.

The researchers, although seeking for further results and tests to link to humans, proposed that women who have a family history of breast cancer should avoid working in shifts that may cause sleep disorder. Hence, van der Horst stated that behind the difficulty of providing further results to link the discovered consequences to humans, the study could be relevant as the researchers determined the circadian or body clock of the mice subjected in the study is comparable to man’s cycle.

"One of the questions we often get is to what extent does a mouse resemble humans," he said, then added that "the mechanism of the circadian clock as well as carcinogenesis is comparable in mice and man, and this model opens new avenues for further exploring how circadian disruptions affect the body and how you can intervene to reduce adverse effects."

According to the report, critics of human circadian disruption studies have considered that lifestyle factors are the possible contributor to the increased health risk.

To contact the writer, email: darwin.malicdem@ibtimes.tunemedia.biz