Two large studies presented at the American Society of Clinical Oncology's annual meeting in Chicago suggest that poor sleep may be contributing to the global rise in cancer diagnoses among people under 50. Worldwide cases of early-onset cancer increased from 1.82 million in 1990 to 3.26 million in 2019, while cancer deaths in this age group rose by 27%.
Researchers from Jefferson Health New Jersey and Ochsner MD Anderson Cancer Center analysed health data from over 18 million US adults aged 18 to 50. They found that individuals with poor sleeping patterns were more likely to develop early-onset bowel, breast, uterine or ovarian cancer. In some cases, under-50s diagnosed with insomnia were three times more likely to develop cancer within five years.
The researchers stated that sleep disruption may represent a clinically relevant, potentially modifiable risk factor for early-onset cancer, warranting further investigation. Experts not involved in the studies welcomed the findings but cautioned that the research showed an association, not proof that poor sleep causes cancer.
Dr David Garley, a GP and director of the Better Sleep Clinic in Bristol, noted that sleep deprivation can lead to unhealthy behaviours such as increased drinking, obesity, and smoking, which may themselves raise cancer risk. He also highlighted that sleep plays a role in restoring the immune system, which could affect cancer development.
Megan Winter, a health information manager at Cancer Research UK, said more research is needed before drawing conclusions. She advised that people can reduce their cancer risk by not smoking, maintaining a healthy weight, and staying safe in the sun.
