DSIP

What it is

DSIP — Delta Sleep Inducing Peptide — is a nine-amino-acid peptide with the sequence Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu. It was identified by what was, even at the time, an unusual experimental approach: collecting cerebral venous blood from rabbits during electrically induced "delta" (slow-wave) sleep and testing fractions of that blood for sleep-inducing activity when infused into recipient animals.

The peptide takes its name from the EEG signature it was originally associated with — high-amplitude delta waves characteristic of deep non-REM sleep — though subsequent work has complicated that single-function picture considerably.

History

Marcel Monnier and Guido Schoenenberger at the University of Basel published the isolation of DSIP from rabbit cerebral venous blood in 1977. The synthetic version was prepared shortly afterward and used in the first human studies in the early 1980s. Schneider-Helmert and Schoenenberger's 1981 paper in Experientia reported improvements in disturbed sleep in clinical populations after intravenous DSIP.

Through the 1980s and into the 1990s, DSIP became one of the more intensively studied neuropeptides. Reported activities expanded well beyond sleep induction to include modulation of stress responses, attenuation of withdrawal symptoms in opioid and alcohol dependence, analgesia, and modulation of pituitary hormone release. Reviews from Graf and Kastin in 1984 and 1986 catalogued more than a hundred reported effects.

Despite the volume of research, no consistent receptor, no convergent mechanism, and no reproducible large clinical effect ever emerged. A 2006 Kovalzon and Strekalova review in the Journal of Neurochemistry, summarizing nearly three decades of work, titled itself "a still unresolved riddle" — a fair characterization. No commercial drug development program advanced DSIP to a registration trial, and interest in the peptide has receded substantially in mainstream neuroscience since the early 2000s.

Regulatory status

Not approved by any regulator. No active registered human clinical trials of DSIP as a therapeutic candidate as of 2026. Not on the FDA 503A bulk substances list; compounding pharmacies in the United States cannot legally prepare it for patients. Sold through research peptide channels with not-for-human-use labeling. Use within sport may be subject to anti-doping rules depending on jurisdiction and intent of use.

How researchers describe its action

The unusual feature of DSIP is the absence of a clear receptor. After five decades of work, no specific high-affinity binding site has been definitively characterized, and proposed mechanisms have ranged from direct GABA-A modulation to opioid-receptor interactions to ACTH and corticosteroid axis modulation to nonspecific anti-stress effects.

The Kovalzon and Strekalova 2006 review summarized the situation: DSIP's effects are real in some assays, the doses required vary by orders of magnitude across studies, and no single mechanism explains the reported behavioral and physiological responses. This is part of why DSIP has remained on the fringe of formal drug development — there is no clean target for pharmaceutical optimization.

Half-life and dosing intervals

Published estimates of DSIP's plasma half-life are very short — roughly 7 to 15 minutes after intravenous administration in rodents. Given the lack of an established receptor and the unusual persistence of behavioral effects beyond what such a short half-life would predict, the relationship between plasma concentration and biological activity remains poorly characterized.

There is no established human dose. The clinical studies from the 1980s used intravenous doses of approximately 25 nmol/kg over short infusions; that route is no longer used in practice. Observational subcutaneous protocols described online typically range from 100 to 500 mcg per day, with administration in the evening reflecting the historical association with sleep. No controlled human pharmacokinetic data supports these specific regimens.

Reconstitution example

DSIP is typically supplied lyophilized in 2 mg or 5 mg vials. A 5 mg vial reconstituted with 2 mL of bacteriostatic water yields 2.5 mg/mL. On a 1 mL U-100 insulin syringe, 4 units (0.04 mL) delivers 100 mcg, and 8 units (0.08 mL) delivers 200 mcg. Vial's calculator handles the conversion when vial mass and water volume are entered.

What to know

• Decades of research, no approval. DSIP has been studied for five decades without converging on a defined mechanism or producing a regulator-approved indication.
• No clear receptor. Unlike most peptides in this library, DSIP has no identified high-affinity binding site. This is a substantive obstacle to formal drug development.
• Heterogeneous published effects. Reported activities span sleep, stress, pain, addiction, and endocrine function. The breadth is itself a sign that no single mechanism captures the biology.
• Very short half-life. Plasma clearance is rapid. Subcutaneous bolus dosing has not been characterized in controlled human trials.
• Storage. Lyophilized: refrigerate, protect from light. Reconstituted: refrigerate; the short unprotected sequence degrades faster than albumin-bound analogs.
• Safety profile is incomplete. Short-term tolerability appears reasonable in the historical clinical studies, but long-term human safety data does not exist.