Narcolepsy type 1, which is caused by loss of hypothalamic orexin-producing neurons, is a rare sleep disorder characterized by excessive daytime sleepiness, cataplexy, and sleep disorders. Genetic and environmental factors play a major role in the pathogenesis of narcolepsy, especially in people with HLA-DQB1?06:02 alleles. Substantial genetic and epidemiological evidence points to the immune system, for instance, a significantly increased incidence of narcolepsy was seen after the pandemic H1N1 influenza and vaccination, suggests that H1N1 may contribute to the development of NT1, but the exact mechanism of hypothalamic neuron injury by the immune system is not well understood. Autoreactive T cells against orexin neurons have been detected in samples of patients with NT1, in which helper CD4⁺ T cells and cytotoxic CD8⁺ T cells may be pathological, indicating that NT1 pathogenesis is related to T cell-mediated autoimmunity. This article reviews the recent research progress in the pathogenesis of narcolepsy type 1 induced by T cells.