Insomnia Triples Cancer Risk in Under-50s, Studies Find

The findings arrive amid a global surge in 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 among people in their 30s and 40s climbed 27%. In the United Kingdom, bowel cancer has jumped 22% among adults aged 25 to 49. The new research found that women with insomnia faced three times the risk of breast cancer, almost double the risk of uterine cancer, and a 57% higher risk of ovarian cancer; both sexes were twice as likely to develop bowel cancer. No similar link appeared between insomnia and hormonal cancers in men, such as prostate or testicular disease. The researchers suggest that disrupted sleep may interfere with hormone balance, while independent experts add that poor sleep can also weaken the immune system's ability to suppress abnormal cells.

Independent experts welcomed the work but cautioned that the studies show association rather than proof of cause. Dr David Garley, director of the Better Sleep Clinic in Bristol, noted that poor sleepers often drink more, exercise less, and carry more weight — habits that themselves raise cancer risk. Claire Coughlan of Bowel Cancer UK said the conclusions were "worth exploring further", while Megan Winter of Cancer Research UK urged longer-term studies before clinical advice changes. For now, she said, people can lower their cancer risk by not smoking, maintaining a healthy weight, and protecting their skin in the sun. The researchers hope their findings will eventually inspire targeted lifestyle interventions for younger adults at risk.