Working late at night, flying across time zones often, or keeping an irregular sleep schedule may do more than just leave you tired—it might actually raise your risk of developing aggressive breast cancer.
A new study led by Dr. Tapasree Roy Sarkar at Texas A&M University has uncovered how disruptions to our internal body clock, known as the circadian rhythm, can speed up cancer growth and weaken the body’s ability to fight it.
The circadian rhythm is our body’s natural 24-hour clock. It controls much more than just sleep—it also helps regulate hormones, repair body tissues, and manage our immune system.
When that clock is thrown off, as happens with shift work or irregular sleep, important body functions can go out of sync. The new study found that this disruption can actually make the body more vulnerable to cancer.
Researchers used specially bred animal models that are likely to develop aggressive breast cancer. One group followed a normal day-night schedule, while the other had their light cycles changed regularly to mimic circadian disruption.
The results were alarming. The group with disrupted sleep patterns developed cancer earlier—about four weeks sooner—and the cancer spread more quickly, especially to the lungs.
The immune system, which usually helps stop cancer from growing, was also weakened in the disrupted group. The researchers found that changes in normal breast tissue made it easier for cancer to grow. The structure of the mammary glands, which produce milk, had changed in unhealthy ways due to long-term sleep disruption.
When the researchers looked deeper into the tumors, they found a key immune molecule called LILRB4. This molecule usually helps keep inflammation under control in healthy conditions.
But in cancer, it acts like an “off switch” for the immune system, making it easier for cancer cells to grow and spread. When the scientists blocked LILRB4 in their study, the immune system became more active again—even under disrupted sleep conditions—and cancer spread was reduced.
This discovery opens the door to a new way to treat breast cancer, especially in people who work night shifts or have irregular sleep. By targeting LILRB4, doctors might be able to reduce cancer risk or improve treatment, even when a person’s sleep cycle can’t be fixed easily.
Dr. Sarkar and her team believe this is one of the strongest proofs yet that poor sleep schedules don’t just go hand in hand with cancer—they may actually drive it.
Their study suggests that keeping a healthy sleep routine could help protect against cancer, and that fixing the body’s clock—or blocking its harmful effects—could become part of cancer treatment in the future.
This research is especially important for the millions of people who work night shifts, travel often, or have jobs with rotating hours. The team’s next goal is to study how to reverse these harmful effects in humans. Their mission is clear: to improve real-world health outcomes and help protect people who live and work outside the traditional 9-to-5 schedule.
This groundbreaking research shows that cancer does keep time—but now, scientists are learning how to turn back the clock.
If you care about breast cancer, please read studies about how eating patterns help ward off breast cancer, and soy and plant compounds may prevent breast cancer recurrence.
For more health information, please see recent studies about how your grocery list can help guard against cancer, and a simple way to fight aging and cancer.
The study is published in Oncogene.
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