Insomnia is a widespread sleep disorder that poses a significant risk to both physical and mental health.[1] Mendelian randomization is a scientific method that uses genetic data to detect true causal relationships between insomnia and disease, overcoming the limitations of traditional studies, which often fail to determine the direction of causation.[1] An analysis of 105 Mendelian randomized trials showed that insomnia has a clear causal effect on several diseases, including coronary heart disease, anxiety-depressive disorders, type 2 diabetes, and chronic pain.[1] Studies have also confirmed causal relationships with osteoarthritis and lung cancer, although with a smaller magnitude of effect.[1] Conversely, associations with Alzheimer's disease and schizophrenia have not been confirmed.[1] Research has clearly demonstrated that the causal direction runs from insomnia to disease, effectively correcting for the potential reverse causation bias observed in traditional research.[1] These findings point to insomnia as a key modifiable cause of a range of psychosomatic disorders and provide a scientific basis for early prevention and treatment in high-risk populations.[1]