Poor sleep linked to rising cancer risk in people under 50, studies suggest

Poor sleep may be contributing to the growing number of cancer cases among adults under 50, according to two large studies presented at the American Society of Clinical Oncology's annual meeting in Chicago.

Researchers from MD Anderson Cancer Center in Houston analysed health data from more than 18 million adults in the United States aged between 18 and 50. They found that people with poor sleeping patterns were more likely to develop early-onset bowel, breast, uterine, or ovarian cancer.

In some cases, adults under 50 diagnosed with insomnia were found to be up to three times more likely to develop cancer within five years.

The findings come as scientists continue to investigate the reasons behind a sharp rise in cancer cases among younger adults. Worldwide, early-onset cancer cases increased from 1.82 million in 1990 to 3.26 million in 2019, while cancer deaths among people under 50 rose by 27 per cent during the same period.

Researchers said sleep disruption could represent a potentially modifiable risk factor for early-onset cancers, though they stressed that further investigation is needed.

Experts welcomed the research but cautioned that the studies identified an association rather than proving that poor sleep directly causes cancer.

Claire Coughlan, clinical lead at Bowel Cancer UK, said the findings could help researchers better understand the increase in bowel cancer among younger people, although the reasons remain unclear.

Dr David Garley, director of the Better Sleep Clinic in Bristol, said poor sleep may affect the immune system and make it harder for people to maintain healthy lifestyles, factors that could influence cancer risk. He also noted that undiagnosed cancer itself could potentially affect sleep patterns.

Megan Winter of Cancer Research UK said more long-term research is needed before firm conclusions can be drawn about the relationship between insomnia and cancer risk in younger adults.