Two large studies presented in Chicago have linked poor sleep patterns with a higher risk of early-onset cancer in adults under 50, adding a new piece to the puzzle of why diagnoses are rising in younger people. The research, led by MD Anderson Cancer Center in Houston, suggests that insomnia and disrupted sleep may be part of the story behind the global rise in cancers diagnosed before middle age.
The findings were unveiled at the American Society of Clinical Oncology annual meeting, where researchers have been looking for clues to explain why early-onset cancer has become more common. Worldwide cases rose from 1.82 million in 1990 to 3.26 million in 2019, while deaths among people in their 40s, 30s or younger climbed by 27%. More than 1 million under-50s die from cancer each year, according to research published in BMJ Oncology, which has intensified interest in factors that might be changed before disease takes hold.
The studies analysed health data for more than 18 million adults in the US aged 18 to 50 and found that people with poor sleeping patterns were more likely to develop 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 said sleep disruption may represent a clinically relevant, potentially modifiable risk factor in early-onset cancer risk stratification, and that it warrants further investigation.
Claire Coughlan said bowel cancer was still more common in over-50s, but added that there was a growing body of evidence globally showing cases increasing in younger people. She said the study’s conclusion that insomnia may be a potential risk factor in early-onset colorectal cancer could help explain that rise, and said the findings were worth exploring further. Her view reflects the wider concern among cancer specialists that younger adults are being diagnosed more often even as the disease remains far more common in older age groups.
But the studies stop short of proving that poor sleep causes cancer. David Garley said they identified an association rather than proof of causation, and pointed to other possible explanations, including drinking, obesity, less exercise and smoking, which can become more common when people are sleep-deprived. He also said sleep helps restore the immune system, suggesting a biological route by which disturbed rest could play a part without being the only factor involved.
That leaves the central question open: whether sleep disruption is a direct driver of early-onset cancer, or a marker for other risks that travel with it. What the research does establish is that poor sleep has moved from a general health concern to something cancer researchers are now treating as a possible piece of the under-50s puzzle, and the next step will be testing how much weight it really carries.
