DSIP (Delta Sleep Inducing Peptide) Research Peptide Midwest Peptide The effect of delta sleep inducing peptide (DSIP) and phosphorylated DSIP (P DSIP) on the apomorphine induced hypothermia in rat DSIP (Delta SleepInducing Peptide) is a naturally occurring neuropeptide first isolated in 1974. It's best known for its potential role in regulating sleep, stress, and neuroendocrine function. Here's a clear breakdown of Half Life : Delta Particles (Steam), Ch. 2 "Exit to the Surface" Half Life: Blue Shift on Steam