Disrupted sleep cycles caused by night shifts, frequent long-haul travel or irregular schedules may do more than trigger fatigue—they can actively drive the development and spread of aggressive breast cancer, according to a new study from Texas A&M University.

Published in ‘Onco – gene,’ the research shows that circadian disruption alters breast tissue structure and suppresses the immune system, creating conditions that allow cancer to grow faster and spread more easily.

“Cancer keeps time. If your internal clock is disrupted, cancer takes advantage—but now we’ve found a new way to fight back,” said lead researcher Dr. Tapasree Roy Sarkar, CoDirector of the Center for Statistical Bioinformatics at Texas A&M University.

Circadian rhythms, the body’s internal 24-hour clock, regulate sleep, hormones, tissue repair and immune surveillance. When this rhythm is disturbed, the body’s natu – ral defences weaken. “The circadian rhythm orchestrates how our tissues function, and how our immune system recognises danger,” Sarkar explained.

“When that rhythm is disrupted, the consequences can be seriously dangerous.” Using two groups of genetically engineered models prone to aggressive breast cancer, researchers found that those exposed to disrupted light–dark cycles developed cancer earlier—around 18 weeks instead of the typical 22 weeks.