Description_x000D_ Amino Acid Sequence_x000D_ Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu-OH_x000D_ General description_x000D_ Delta sleep inducing peptide (DSIP) is a nonapeptide which was isolated from the rabbit brain. It is synthesized in the hypothalamus and is present in small amounts in the blood._x000D_ Biochem/physiol Actions_x000D_ DSIP promotes sleep by targeting various areas of the brain. The peptide is easily absorbed from the gut and is not denatured by enzymes. It crosses the blood-brain barrier easily. DSIP influences the circadian rhythm in humans. Low concentrations of the peptide are observed in patients with schizophrenia and depression.