Every cell in your body follows a 24-hour schedule known as a circadian rhythm. This schedule is controlled by a master clock in your brain, located in an area called the suprachiasmatic nucleus.
The circadian clock helps regulate important functions like sleep, metabolism, hormones, and even the immune system.
But when this clock is out of sync—such as from shift work, poor sleep, or irregular eating—your risk of serious health issues, including cancer, may go up.
Professor Chi Van Dang, a cancer medicine expert at Johns Hopkins University and a leader at the Ludwig Institute for Cancer Research, has spent years studying how cancer cells grow and behave.
He became especially interested in how cancer and circadian rhythms interact when he discovered that MYC, a gene linked to many cancers, works on the same parts of DNA as the body’s internal clock genes.
This raised an exciting question: Could cancer and circadian systems be linked in a way that affects how tumors grow—and how we treat them? Over the years, Dang and his team have uncovered more and more evidence that this connection is real and important.
One of the most eye-opening findings is that some types of cancer seem to grow faster when the circadian rhythm is disrupted. For example, mice exposed to artificial light patterns that mimic night shift work developed more tumors.
Studies of human tumors also show that in cancers like breast, liver, and lung cancer, the body’s clock appears to be broken. Interestingly, not all cancers respond the same way. For some cancers like leukemia and brain cancer, disrupting the clock actually slowed their growth.
This research is leading to a new idea in cancer care: timing treatments to match the body’s internal clock, a concept called “chronotherapy.” Some cancer drugs work better or cause fewer side effects if given at the right time of day.
For instance, radiation treatment in the morning may cause fewer side effects than the same treatment in the afternoon. For immunotherapy, which helps the immune system fight tumors, recent studies show that patients who get treated in the morning tend to do better than those treated later in the day.
This might be because the immune system also follows a daily rhythm. Cells that fight cancer enter the tumor more often in the morning. So, giving the treatment when those cells are already active makes it more effective.
Despite these promising results, making treatment schedules fit the circadian clock is still a challenge. Hospitals can’t always give treatments at specific times for every patient. But future solutions could include at-home treatment delivery or medicines that help “reset” a patient’s internal clock.
Time-restricted eating, where food is only eaten during certain hours of the day, might also help the body’s clock function better. Early research shows that this kind of diet can slow tumor growth and improve how the body responds to treatments like immunotherapy.
The impact of circadian rhythms goes far beyond cancer. Common drugs like aspirin and statins (used for lowering cholesterol) work better when taken at night. That’s because the liver enzymes that process these drugs rise and fall throughout the day. Timing matters, not just for what you take, but when you take it.
Making this timing-based approach work will take help from many people—doctors, researchers, medicine makers, and patients. Education is key. Doctors need to know how timing affects health, and they need to teach patients the best times to take medications or eat meals.
Pharmaceutical companies also have a role to play. When developing new drugs, they should test how the body processes them at different times of day. Understanding a drug’s timing could make it safer and more effective.
In his ongoing research, Professor Dang is exploring how breaking the internal clock in different types of cancer affects tumor growth and immune response. Early results show that the effect depends on the cancer type.
For example, in breast cancer, destroying the clock speeds up tumor growth. His team is also studying how meal timing and fasting might “reset” the body’s clock and improve cancer treatments.
In summary, circadian rhythms may hold the key to better health and more effective cancer care. Understanding and using this internal clock could help doctors treat patients more precisely and improve outcomes. The clock inside you may be just as important as the medicine you take.
If you care about cancer, please read studies about a new method to treat cancer effectively, and this low-dose, four-drug combo may block cancer spread.
For more information about cancer prevention, please see recent studies about nutrient in fish that can be a poison for cancer, and results showing this daily vitamin is critical to cancer prevention.
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