DSIP (Delta Sleep-Inducing Peptide)

Ten publications are cited, dating from 1981 to 2021, and six of them date from the 1980s. Three involve people: two 1981 studies of sleep after DSIP was given, one of them in people with disturbed sleep, and a 1987 study that measured DSIP-like immunoreactivity in the cerebrospinal fluid of patients with Alzheimer-type dementia, multi-infarct syndrome, communicating hydrocephalus or Parkinson's disease. The other seven are laboratory work: rat studies of sleep, stroke and chemically induced seizures, a study of rat brain mitochondria and experimental hypoxia, two 1984 papers on the peptide's pharmacology and properties, and a 2014 materials study of a polymer matrix built to hold and release it.

One 1981 study suggested that DSIP sustained natural sleep functions and reported that it was well tolerated, with no psychological, physiological or biochemical side effects observed. The other, in disturbed sleep, found that its sleep-promoting effect appeared only in the second hour after administration, after signs of a slight arousing effect in the first. The 1987 study found lower DSIP-like immunoreactivity than in age-matched controls across several patient groups, with no corresponding difference for the phosphorylated form. In rats, a 2021 study reported faster recovery of motor performance on a rotarod test after focal stroke, and a 2005 study reported antiepileptic activity for DSIP and its analogue DSIP-12 against seizures induced with metaphit. A 2003 study reported more efficient oxidative phosphorylation in isolated rat brain mitochondria, and a 1986 structure-activity study found results consistent with a pseudo-cyclic active molecule and suggested that DSIP may contain a fragment with an arousing effect.

The limits are considerable. The human sleep data are more than 40 years old, and no human study published after 1987 appears among the citations. Each animal finding comes from a single study in one model, and a 1984 pharmacology paper found indications of bell-shaped dose-response curves in most of its experiments, meaning the response rose and then fell as the dose increased. What the record describes is a peptide with a long history in sleep research and scattered recent animal work, not a settled account of how it acts.