Delta sleep-inducing peptide (DSIP) is a nonapeptide with the sequence Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu (WAGGDASGE), molecular weight approximately 848 Da. It was isolated by Schoenenberger and Monnier in 1977 from cerebral venous blood of rabbits placed in electrically induced sleep, and named for the increase in delta-wave EEG activity reported when the fraction was transferred to recipient animals.
Why DSIP is an unusual entry
Nearly fifty years later, no receptor has been cloned or confirmed for DSIP, and no gene encoding a DSIP precursor has been identified — an uncomfortable fact for a molecule with a mechanistic-sounding name. Reported activity is broad and inconsistent across studies: EEG effects, interactions with ACTH and somatostatin release, and antioxidant readouts have all been described, mostly in small rodent studies and a handful of small human series from the 1980s.
It is also short-lived and highly susceptible to proteolysis, and its acidic residues make solution pH a real handling variable. In catalogs it sits with nootropic and sleep-category material, and it should be described as a historically important but mechanistically unresolved research peptide, not as a sleep agent.
Related terms and material
somatostatin · half-life · linear peptide. Reference material: DSIP, sleep & stress peptides. Further reading: what is DSIP and DSIP vs melatonin.