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. The number of early-onset cancer cases worldwide increased from 1.82 million in 1990 to 3.26 million in 2019, while deaths 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 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.
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 noted that poor sleep could lead to unhealthy behaviours such as increased drinking, obesity, and smoking, which may raise cancer risk. He also highlighted that sleep plays a role in restoring the immune system, and its disruption could potentially increase cancer risk.
Megan Winter, a health information manager at Cancer Research UK, said: “These studies explore whether there could be a link between insomnia and some types of cancer in people under 50, but more research is needed, particularly looking at people over longer periods of time, before we can draw any conclusions.” She added that people can reduce cancer risk by not smoking, maintaining a healthy weight, and staying safe in the sun.
