HOUSTON — Researchers at MD Anderson Cancer Center in Houston presented findings at the American Society of Clinical Oncology’s annual meeting in Chicago linking poor sleep patterns and insomnia to a higher risk of early-onset cancer in adults under 50. The two studies analyzed health data from more than 18 million U.S. adults aged 18 to 50 and found that individuals with disrupted sleep were more likely to develop bowel, breast, uterine, or ovarian cancer at a younger age.

People diagnosed with insomnia were three times more likely to develop cancer within five years in some cases, according to the research. Worldwide, early-onset cancer cases rose from 1.82 million in 1990 to 3.26 million in 2019, and cancer deaths among those in their 40s, 30s, or younger increased by 27% over the same period. More than 1 million people under age 50 die from cancer annually, per research published in BMJ Oncology. "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," the researchers said.

Claire Coughlan, clinical lead at Bowel Cancer UK, called the findings worth exploring. "This study’s conclusion that insomnia may be a potential risk factor in early-onset colorectal cancer could go some way to helping us understand the reasons behind this increase. The findings of this study are worth exploring further." She added, "We don’t know exactly why this is yet, but researchers currently believe it may be due to genetics and lifestyle factors."

However, some experts urged caution in interpreting the results. David Garley, a GP and director of the Better Sleep Clinic, noted the studies identified an association but not proof that sleep disruption causes cancer. "There are possible causes from the physiology that arises from poor sleep, but also the fact that when sleep-deprived it’s difficult to live a healthy life – there is more drinking, more obesity, less exercise, more smoking etc – and these may be what causes any possible increased risk." He also said, "If you’re sleeping badly, we know that one of the roles of sleep is restoring the immune system. We’re understanding more about the role of infective agents in the development of cancer. So if your immune system takes a bit of a hit, then I suppose it would make sense that your risk of some cancers may increase. But it also might be the other way around. It could be that if you have cancer, and it’s not yet clinically obvious, it could be causing some change in how you sleep."

Megan Winter, health information manager at Cancer Research UK, emphasized the need for more long-term research. "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." Winter added that people could reduce their cancer risk by not smoking, maintaining a healthy weight, and staying safe in the sun.