Insomnia is a sleep disorder with a high incidence in the world, and its pathogenesis is complex, which is the result of the interaction of genetic predisposition, environmental stress and psychophysiological factors. Epigenetics is considered to be a molecular mechanism that may affect gene expression through the environment, and DNA methylation and N6-methyladenosine (m6A) modification as epigenetic mechanisms can transform environmental stress and other factors into lasting changes in gene expression, and are a molecular bridge connecting external triggers and intrinsic susceptibility to insomnia. This article aims to systematically elucidate the existing evidence on the association between DNA methylation and m6A modification and insomnia, explore the core mechanism of insomnia by affecting the regulation of circadian rhythm and the expression of neurologically related genes, confirm that there are specific epigenetic profile changes in insomnia patients, and propose future research directions to promote the discovery of biomarkers and the translation of epigenetic therapies through multi-omics integration and longitudinal research.