Two large studies suggest that poor sleep may be contributing to the global increase in cancer diagnoses among people under 50. The number of early-onset cancer cases worldwide rose from 1.82 million in 1990 to 3.26 million in 2019, an increase of nearly 80%, while cancer deaths in younger age groups rose by 27%.
Presented at the American Society of Clinical Oncology's annual meeting in Chicago, the studies analysed health data from over 18 million US adults aged 18 to 50. Researchers from Jefferson Health New Jersey and Ochsner MD Anderson Cancer Center found that those 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: “These findings suggest that sleep disruption may represent a clinically relevant, potentially modifiable risk factor in early-onset cancer risk stratification and warrants further investigation.” Experts not involved in the studies welcomed the findings but called for more research to understand the link between insomnia and early-onset cancer.
Claire Coughlan, clinical lead at Bowel Cancer UK, noted that while bowel cancer remains more common in over-50s, cases are increasing in younger people, possibly due to genetics and lifestyle factors. Dr David Garley, a GP and director of the Better Sleep Clinic in Bristol, cautioned that the studies showed an association, not proof that sleep disruption causes cancer. He suggested that poor sleep may weaken the immune system or lead to unhealthy behaviours such as drinking, obesity, and smoking.
Megan Winter of Cancer Research UK said more long-term studies are needed before drawing conclusions. Meanwhile, she advised that people can reduce cancer risk by not smoking, maintaining a healthy weight, and staying safe in the sun.
