Working Night Shifts Can Give You Aggressive Breast Cancer; How Disrupted Sleep Can Be Deadly

Continuously working night shifts, flying across time zones, or keeping an irregular sleep schedule is not just exhausting you but significantly spiking the risk of aggressive breast cancer, says a new

study. According to researchers from the Texas A&M University College of Arts and Sciences, while how and why this happens remains a mystery, the deadly disease takes a toll on your immunity. The study, led by Dr Tapasree Roy and published in the journal Oncology, finds that circadian disruptions change the structure of mammary glands and weaken the immune system's defenses - all the while pointing toward a new way to counteract these effects. “Cancer keeps time. If your internal clock is disrupted, cancer takes advantage—but now we've found a new way to fight back,” said Sarkar, Co-Director of the Center for Statistical Bioinformatics at Texas A&M University College of Arts and Sciences.

How is the circadian rhythm linked to cancer?

A circadian rhythm is your body's natural, 24-hour internal clock that regulates sleep-wake cycles, hormone release, body temperature, and other functions, synchronized by light and darkness. Controlled by your brain's suprachiasmatic nucleus, it manages when you feel alert or sleepy, influencing appetite, metabolism, and energy, and its disruption can cause a lot of physical and mental health issues. According to scientists, circadian rhythms do far more than regulate sleep, and when they are disrupted, your body's natural defences falter. “The circadian rhythm orchestrates how our tissues function, and how our immune system recognizes danger,” Sarkar said. “When that rhythm is disrupted, the consequences can be seriously dangerous.”

How was the study conducted?

To find out how cancer is linked to sleep deprivation, researchers used two groups of genetically engineered models that develop aggressive breast cancer. One group lived on a normal day-night schedule, while the other lived on a disrupted light cycle that threw off their internal clocks. The findings show that typical models developed cancer after more than 20 weeks. While the circadian-disrupted group showed signs of cancer at almost 18 weeks. According to researchers, tumours in sleep-deprived models were also extremely aggressive – so much so that they could spread to the lungs. At the same time, disruption of the models' internal clock suppressed immune defenses, creating a more hospitable environment for cancer growth. “It wasn't just that tumors grew faster,” Sarkar said. “The immune system was actively restrained, creating more favorable conditions for cancer cells to survive and spread.”

What is breast cancer?

Breast cancer is one of the most common cancers that affects women. It happens when cancerous cells in your breasts multiply and become tumours. Doctors say more than 80 per cent of breast cancer cases are invasive, meaning a tumour may spread from your breast to other areas of your body. Breast cancer typically affects women aged 50 years and older, but it can also affect women who are younger. Men may also develop breast cancer.