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Spoke 6.1 · Sleep & Circadian Peptides

DSIP (delta sleep-inducing peptide): what fifty years of research has — and hasn't — resolved.

By PeptideRadar Research Desk  · 
SequenceTrp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu (9 aa) MW~848 Da DiscoveryMonnier & Schoenenberger 1977 FDA statusNot approved; no IND on record Updated2026-04-18

DSIP was named for the effect that made it famous: when infused into wakeful rabbits, venous blood sampled from sleeping rabbits caused them to sleep. Fifty years later, the nonapeptide (Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu) has been found across species, organs, and biological contexts — but its primary receptor remains unidentified, its mechanism of action is disputed, and no Phase II/III human trial has ever been registered. This is an honest account of what is known, what is genuinely unknown, and why the gap matters.

Key points

The discovery: a 1964 hypothesis, a 1977 confirmation

The DSIP story begins not with a peptide but with a transfer experiment. In 1964, Marcel Monnier and Luzius Hösli at the University of Basel (Science, 146(3645):796–798) published results from a cross-circulation experiment in rabbits: blood from sleeping animals infused into wakeful recipients produced EEG evidence of sleep induction. The active factor was clearly humoral — something in blood — but its identity was unknown.

Over the following decade, Georg Schoenenberger joined Monnier's group and the project shifted toward isolation and characterisation. By 1977, Schoenenberger and Monnier published in Proceedings of the National Academy of Sciences USA (74(3):1282–1286) the isolation and characterisation of the nonapeptide they named delta-sleep-inducing peptide, for the delta-wave-dominant sleep stage it promoted when infused into recipient rabbits. The paper described the amino acid sequence Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu and reported consistent sleep-promoting effects that were dose-dependent and reversible.

The 1977 publication is the landmark reference in DSIP science. It is rigorous by the standards of its time. But it immediately raised a question that has never been satisfactorily answered: through what receptor, on what cells, does DSIP produce its effect?

The receptor problem: why this matters for everything downstream

In modern pharmacology, a compound without a confirmed primary receptor is a compound without a complete mechanism. You cannot define potency (Kd), efficacy (Emax), or selectivity — the three numbers that allow rational dose estimation, prediction of off-target effects, and principled design of clinical trials. This is not a semantic issue; it is the reason DSIP has never progressed beyond early human studies.

The candidates that have been proposed over the decades include:

Why the receptor gap is a scientific problem, not a vendor opportunity Some vendor copy frames DSIP's "multi-receptor activity" as evidence of its versatility. The honest reading is the opposite: the absence of a confirmed primary receptor means the compound's mechanism is unknown, dose-response cannot be defined, and selectivity cannot be assessed. This is a scientific limitation, not a feature.

Distribution and endogenous biology

One of the genuinely interesting findings that came out of the post-1977 literature is how widely DSIP is distributed. Graf and Kastin's 1984 review (Neurosci Biobehav Rev, 8(1):83–93) catalogued DSIP immunoreactivity in:

This distribution is inconsistent with a compound whose sole function is sleep induction — or indeed, with a compound that acts only in the central nervous system. It raised the possibility that DSIP is a broader neuromodulator or even a hormonal signal, with sleep effects being one output among several. The functions proposed have included:

This multi-system profile is not evidence of extraordinary breadth of action; it may reflect either a genuinely pleiotropic neuromodulator or, more likely, assay cross-reactivity and the loose coupling that results from acting on widely expressed targets like opioid receptors. The Graf-Kastin review itself notes that the breadth of proposed activities is a reason for skepticism about any single unified mechanism, not a validation of them.

The human data: what was actually done and what it showed

The Schoenenberger group conducted human studies in the late 1970s and early 1980s. Schneider-Helmert and Schoenenberger (1983, Neuropsychobiology, 9(4):197–206) reported that intravenous DSIP infusion in poor sleepers produced improvements in sleep onset latency, sleep efficiency, and stage 3–4 (slow-wave) sleep by polysomnography, alongside self-reported sleep quality improvements. The study was small — a characteristic of the era — and was not placebo-controlled in a fashion that would satisfy modern ICH-E10 standards.

Subsequent attempts to replicate these findings produced inconsistent results. Some studies found modest subjective improvements; others found no polysomnographic effect. Feldman's 1986 review (Neurosci Biobehav Rev, 10(3):315–323) concluded that the evidence was promising but insufficiently replicated to draw clinical conclusions. That assessment has not been superseded by subsequent large-scale trials, because such trials were never conducted.

The Russian literature, represented by groups like Ivanova et al. (2003, Peptides), has continued to investigate DSIP in the context of opioid withdrawal, stress, and sleep architecture, generally finding positive effects. The same geographic-concentration caveat that applies to the Epitalon literature (see our Epitalon circadian spoke) applies here: these studies are real and worth knowing, but they have not been subject to the independent external replication that builds confidence in a finding.

DSIP for stress and pain: the adjacent literature

Because DSIP research in the 1980s identified HPA-axis modulation as a possible mechanism, a parallel literature developed around stress and pain. The logic: if DSIP reduces corticotrophin-releasing factor and cortisol secretion in stressed animals, it might provide a sleep benefit specifically in stress-driven insomnia (which is the most prevalent insomnia phenotype clinically). Steiger's 2002 review (Sleep Med Rev, 6(2):125–138) acknowledged this pathway as one of the more plausible mechanistic accounts, while noting that human evidence for the stress-modulating effect in the context of sleep was limited.

For researchers following the anxiety-sleep overlap — compounds that address sleep disruption through anxiolysis — our Selank for sleep spoke and the peptides for sleep-anxiety comorbidity spoke provide more substantively evidenced alternatives. DSIP's stress-modulating evidence is interesting as hypothesis but does not reach clinical validation.

Practical profile: half-life, stability, and sourcing considerations

DSIP is a nonapeptide (nine amino acids) with an estimated plasma half-life in the range of minutes to a few hours following intravenous administration in animal studies. Like most small peptides, it is subject to rapid proteolytic degradation. The published animal studies used intravenous or intraperitoneal administration; subcutaneous bioavailability has not been quantitatively characterised in humans. Oral bioavailability is almost certainly negligible — peptides of this size are digested before reaching systemic circulation.

Research vials are typically supplied as lyophilized peptide at microgram-to-milligram scale. Reconstitution follows standard bacteriostatic water protocol; dosing in animal studies has ranged from 1 μg/kg to 10 μg/kg IV. Translating these doses to human research settings is not straightforward without confirmed receptor pharmacology. Our DSIP dosing spoke (6.2) covers the animal dose literature and the practical limitations of extrapolation.

Vendor sourcing: as with all research peptides, a legitimate COA should include HPLC purity ≥98%, mass-spec identity confirmation (molecular weight ~848 Da for the free peptide), lot number, and manufacture date. DSIP's small size makes it easier to synthesise than longer peptides, which means the market supply is somewhat broader — but this also means QC verification is no less important. Our DSIP side effects spoke (6.18) covers the available safety data.

Context in the Sleep & Circadian cluster

Within the Sleep & Circadian pillar, DSIP occupies the "direct sleep induction candidate" family alongside Pinealon and VIP. Its position as the cluster's namesake compound does not correspond to being its best-evidenced compound — that distinction belongs to MK-677 (Copinschi 1997), through an indirect GH-pulse mechanism. DSIP's relationship to other sleep spokes:

For the pineal/circadian angle — the mechanism adjacent to DSIP that involves melatonin specifically — our Epitalon circadian spoke is the primary reference, and the Pinealon for sleep spoke (6.22) covers the companion peptide bioregulator. Cross-pillar, the closest mechanistic relative in the Cognitive cluster is the Pinealon cognitive spoke (2.12).

Where to read further

Primary and review references, current to 2026-04:

Frequently asked

Is DSIP FDA approved?
No. DSIP has never been FDA-approved as a drug. No Investigational New Drug (IND) application for DSIP is on public record in the United States as of April 2026. It is sold by research-chemical vendors under a research-use-only framing. This is not a compound that has passed Phase II or III human trials — it has not passed Phase II in any Western regulatory jurisdiction.
What does DSIP actually stand for?
Delta Sleep-Inducing Peptide — named for its purported ability to enhance delta-wave (slow-wave, stages 3–4) sleep in the original rabbit cross-circulation experiments of Monnier and Schoenenberger (1977). The "delta" refers to the EEG frequency band (0.5–4 Hz) characteristic of deep slow-wave sleep, not to a receptor subtype.
Why doesn't DSIP have an identified receptor?
Identifying a primary receptor requires demonstrating saturable, high-affinity binding to a specific protein that can be linked to the compound's in vivo effects. For DSIP, no such demonstration has been achieved despite decades of research. Proposed candidates — opioid receptors, benzodiazepine binding sites, calcium channels — have not produced a consistent mechanistic account that explains all DSIP effects across preparations. Without receptor identification, neither potency nor selectivity can be defined, and rational clinical trial design is not possible.
How does DSIP compare to melatonin for sleep?
Melatonin is incomparably better evidenced. Melatonin acts on well-characterised MT1/MT2 receptors with defined Kd values; it has dozens of randomised controlled trials for circadian rhythm disorders and jet lag; and it is approved as a medication in multiple jurisdictions. DSIP has small, old, unreplicated human studies and no confirmed primary receptor. For sleep interventions, melatonin is the appropriate benchmark; DSIP's evidence does not approach it.
Is the Russian DSIP literature reliable?
The Russian DSIP literature is real science conducted by identifiable researchers at named institutions — not pseudoscience. The limitation is that geographic concentration of research reduces confidence in findings, because errors in method, assay calibration, or interpretation are less likely to be caught than when multiple independent groups work on the same question. The appropriate posture is to treat Russian-origin DSIP data as hypothesis-generating rather than confirmatory, in the same way one would treat a single-lab finding in any other research area. This is the same caveat that applies to the Epitalon circadian literature.
Can DSIP be used with other sleep peptides?
No stacking has been studied in human trials. The theoretical interaction between DSIP and GH-secretagogues (MK-677, CJC-1295) is undefined — they operate through different proposed mechanisms, so pharmacological interference is not expected, but neither is an additive effect established. Our stacking spoke (6.25, DSIP stack with CJC-1295) covers the rationale and its limitations.
Reviewer sign-off Reviewed 2026-04-18 by the PeptideRadar Research Desk for RUO compliance, mechanism accuracy, and citation integrity. DSIP evidence grading: pre-Phase II. No receptor identified. Human data fragmentary and unreplicated at scale. This article does not imply efficacy, safety, or fitness for human use. Corrections policy: errors are flagged in a dated note appended to this article, not silently edited. Contact: corrections@peptideradar.net.

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