When Tumours Throw Off Your Body Clock: New Study Links Cancer to Disrupted Day–Night Rhythms

Patients’ sleep and energy suffer when cancer changes the brain’s timing

A new study suggests that cancer does more than grow where it shouldn’t. It can also nudge the brain’s internal clock, the system that tells us when to sleep, eat and feel alert. The work helps explain why people with cancer often complain of severe fatigue, strange sleep patterns and an odd mismatch between their body and the day outside. The finding matters because these problems can make treatment harder and life much worse — and because they may point to new ways to ease symptoms, even if the tumour itself hasn’t changed yet.

What the researchers actually did and found

The team ran experiments in mice that had been given tumours similar to human cancers. They watched the animals’ behaviour across day and night, measured brain activity, and looked at chemicals in the blood known to carry immune messages. The mice with tumours began to show clear changes in when they slept and how active they were. Some animals grew quieter in the daytime, others had broken-up sleep at night, and many showed an overall loss of normal daily patterns.

Inside the brain, the researchers focused on regions that set the body’s daily rhythm. They recorded nerve-cell activity and found that patterns that usually rise and fall with the day were flattened or shifted in tumour-bearing animals. At the same time, blood tests showed higher levels of immune proteins that signal inflammation. When the team blocked a key inflammatory signal in some mice, parts of the brain’s daily rhythm began to recover. That suggests the tumours were changing behaviour partly by sending inflammatory messages into the circulation — not just by pressing on the brain.

The study mixed behavioural recording, brain measurements and simple intervention tests. Together, these steps give more than a rough link: they show a plausible chain from tumour to blood-borne signals to altered brain timing and then to disturbed sleep and activity in the animals.

How cancer might tug on the brain’s clock

Our daily rhythm — often called the circadian system — depends on a handful of brain regions that talk to each other and to the rest of the body. The new study points to inflammation as the bridge between tumours and those brain regions. Tumours release or trigger the release of immune molecules. Those molecules travel in blood and can reach brain areas that control sleep and wakefulness.

Once such signals arrive, they shift how neurons fire across the day. Instead of a clear daytime rise in alerting signals and a nighttime fall, the pattern becomes muted or out of sync. That blurs the line between day and night inside the brain, so the body may feel tired at odd times and restless at others. The researchers also suggest that tumours could change metabolic cues — like how much fuel is available to cells — which in turn can nudge the clock. Both immune and metabolic signals can, in simple terms, confuse the timing circuits.

What this means for people living with cancer

For patients, these findings put a name and a mechanism to what many already feel: overwhelming fatigue, sleep that doesn’t refresh, and a sense that the body’s schedule no longer matches the world. If tumours are actively sending signals that scramble the clock, then some sleep and fatigue problems may not be only psychological or side effects of treatment — they can be direct effects of the disease itself.

That matters because disrupted rhythms make it harder to tolerate chemotherapy, keep a normal appetite, and stay physically active. The study hints at ways clinicians might help: reducing inflammatory signalling, timing treatments to moments when the body’s clock still works best, or using treatments that support regular day–night cues. Those are ideas worth testing in people, and they could lead to symptom-relief strategies that improve daily life even without curing the cancer.

What the study cannot yet prove and where to go next

These results are strong in animals, but mice are not people. The tumour types used in the lab are models, not every human cancer. The study shows a likely chain of events, but it does not yet prove the same chain runs in every patient. Sample sizes in animal work are also smaller than big human studies, and blocking one inflammatory pathway helped in mice but might not work the same way in people.

Future work should test whether similar molecules and brain changes appear in patients, whether different cancers behave differently, and whether targeted treatments can restore normal rhythms and ease symptoms. Clinical trials will be needed to move from animal evidence to care that helps people.

Voices from the research and how this fits into the bigger picture

The authors describe their results as “a clear link between tumours and the brain’s timing system,” and they emphasize that inflammation appears to be a key messenger. One passage in the paper notes that treating the inflammatory signal partially reversed rhythm disruption in animals, which the team calls a promising first step.

Outside this study, scientists have long suspected a two-way connection between body clocks and disease. Poor sleep can worsen immune function, and chronic illness can throw sleep off. This new work puts cancer on that map more firmly by showing how tumours themselves can drive the mismatch. If future human studies confirm the effect, the finding could change how clinicians think about symptom care — shifting some focus from managing downstream fatigue to treating the signals that create it.

Sources

• prnewswire.com