DSIP is an amphiphilic peptide of molecular weight 850 daltons with the amino acid motif: N-Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu-C.

Delta sleep-inducing peptide, abbreviated DSIP, was first discovered in 1974 by the Swiss Schoenenberger-Monnier group who isolated it from the cerebral venous blood of rabbits in an induced state of sleep. It was primarily believed to be involved in sleep regulation due to its apparent ability to induce slow-wave sleep in rabbits, but studies on the subject have been contradictory.

It has been found in both free and bound forms in the hypothalamus, limbic system and pituitary as well as various peripheral organs, tissues and body fluids.[3] In the pituitary it co-localises with many peptide and non-peptide mediators such as corticotropin-like intermediate peptide (CLIP), adrenocorticotrophic hormone (ACTH), melanocyte-stimulating hormone (MSH), thyroid-stimulating hormone (TSH) and melanin concentrating hormone (MCH). It is abundant in the gut secretory cells and in the pancreas where it co-localises with glucagon