Shi T, et al. - Researchers explored the connection between insomnia and cancer. Eight cohort studies including 578,809 candidates and 7,451 cancer events were incorporated into the analysis after a strict screening. The data presented in this work showed a 24% overall increased risk of cancer for people with insomnia vs those without insomnia. The risk of developing cancer was significantly greater in studies conducted in women, but not men, as seen in subgroup analyses. Pooled HR was only significantly greater in thyroid cancer, but not in other cancer types. The results indicate that insomnia can serve as an early warning sign of the onset of cancer and provide early detection and early intervention opportunity. Due to the limited number of included studies and potential bias, the findings should be treated with caution.