Delta sleep-inducing peptide, abbreviated DSIP, is a neuropeptide that when infused into the mesodiencephalic ventricle of recipient rabbits induces spindle and delta EEG activity and reduced motor activities. DSIP was discovered by G.Schoeneberger and M.Monnier in 1974; first research aimed at it's somnogenous properties lead to the dubious results. Instead it was demonstrated by the works of different teams that DSIP actually plays a important role in the stress-resistance. DSIP has stress-protective, antiseizure, and immunomodulating effects. It has been demonstrated that DSIP have significant geroprotective effect. K.V. Sudakov views DSIP as one of the 4 main substances, responsible for the stress-resistance of the organism, another 3 being substance P, prolactin and beta-endorphin.