Quick Answer
DSIP (delta sleep-inducing peptide), also called emideltide, is a nine-amino-acid neuropeptide first isolated from rabbit brain tissue in 1977, studied primarily for sleep modulation, opioid withdrawal, and stress response. It was removed from FDA Category 2 on April 15, 2026 and is scheduled for PCAC review on July 24, 2026 for three indications: opioid withdrawal, chronic insomnia, and narcolepsy.
| DSIP / Emideltide – Compound Identity | |
|---|---|
| Full name | Delta sleep-inducing peptide (DSIP) / Emideltide |
| Sequence | Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu (WAGGDASGE) |
| Type | Nonapeptide (9 amino acids) |
| CAS number | 62568-57-4 |
| Molecular weight | 848.81 g/mol |
| Discovery | Schoenenberger and Monnier, University of Basel, Switzerland (1977) |
| Endogenous distribution | Hypothalamus, limbic system, pituitary gland, gut, pancreas (co-localises with glucagon), blood plasma (free and bound forms) |
| FDA regulatory name | Emideltide (Federal Register designation) |
| Category | Neuropeptide (cognitive and neuropeptide cluster) |
What Is DSIP and Where Did It Come From?
DSIP is a naturally occurring nonapeptide that was the first substance ever isolated from brain tissue specifically because of its observed sleep-promoting properties. The discovery story begins in the early 1960s at the University of Basel, Switzerland, where Marcel Monnier and Gerhard Schoenenberger conducted a series of cross-circulation experiments on rabbits. They connected the blood supply of a sleeping rabbit to an awake recipient and observed that the awake rabbit’s brainwaves shifted toward slow-wave delta activity. Something in the blood was carrying a sleep signal.
It took until 1977 to isolate, sequence, and synthesise the responsible molecule. The team published their findings in the Proceedings of the National Academy of Sciences, identifying a nonapeptide with the sequence Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu. When tested under double-blind conditions, the synthetic version produced a 35% increase in delta EEG activity in rabbits following intraventricular infusion. They named it “delta sleep-inducing peptide.”
DSIP is not confined to the brain. It has been detected in the hypothalamus, limbic system, pituitary gland, peripheral organs, blood plasma, cerebrospinal fluid, and the gut, where it co-localises with glucagon in pancreatic cells. In the pituitary it co-localises with ACTH, MSH, TSH, and melanin-concentrating hormone. This widespread distribution was one of the first hints that the peptide’s biological role extended well beyond sleep.
The bottom line: DSIP was isolated through an elegant cross-circulation experiment in Switzerland and remains one of the few neuropeptides identified specifically because of a behavioural observation rather than through receptor-based screening.
How Does DSIP Work?
The mechanism of DSIP remains incompletely understood, which is the central scientific problem that has followed the peptide for nearly five decades. Unlike most therapeutic peptides, DSIP does not have a single well-characterised receptor. Instead, research suggests it modulates multiple brain systems involved in sleep regulation, stress response, and neuroendocrine function.
The available mechanistic data points toward several targets. DSIP appears to influence the GABAergic system, with preclinical evidence showing it can prevent convulsive onset induced by GABA-A antagonists. It modulates serotonin, noradrenaline, and histamine systems. Preclinical models have shown it increases substance P concentrations in the hypothalamus, a neuropeptide positively correlated with anxiety and mood regulation. It also influences cortisol release, LH, GH, and ACTH secretion, establishing it as a compound with broad neuroendocrine activity.
A 1984 hypothesis by Tissot proposed that DSIP possesses agonistic activity on opiate receptors. Tissot demonstrated that morphine, alcohol, pentobarbital, and DSIP all induced slow-wave sleep with spindles when injected into the bulbo-mesencephalo-thalamic recruiting system, and that the effect of each was reversed by the opioid antagonist naloxone. This finding became the rationale for DSIP’s investigation in substance withdrawal.
A 2001 editorial in the European Journal of Anaesthesiology by Pollard and Pomfrett speculated that DSIP and other neuroactive peptides may selectively bind to the same receptor regions where volatile anaesthetic agents, ketamine, and xenon act – specifically sites on GABA-A, glycine, and NMDA receptors. This hypothesis remains untested but would help explain DSIP’s broad activity profile.
The half-life problem is fundamental. DSIP is rapidly degraded by brain aminopeptidases, with studies documenting a half-life of approximately 15 minutes when exposed to enzymatic activity. A 1990 study by Nyberg and colleagues identified a specific aminopeptidase in human cerebrospinal fluid that degrades DSIP. The peptide appears to circulate in both free and carrier-bound forms, with the bound form potentially providing some protection against rapid breakdown.
The bottom line: DSIP’s lack of a single defined receptor target has been both its scientific mystery and its commercial barrier. As Kovalzon and Strekalova wrote in their 2006 Journal of Neurochemistry review, DSIP remains “a still unresolved riddle.”
What Does the Evidence Actually Show?
The human evidence for DSIP is concentrated in the 1980s and early 1990s, with no modern clinical trials meeting current regulatory standards. The available data spans three main therapeutic areas – the same three now under PCAC review.
Sleep and insomnia
Schneider-Helmert, working alongside Schoenenberger at the University of Basel, conducted a series of clinical studies through the 1980s. A 1981 study in Experientia reported that synthetic DSIP improved disturbed sleep, with effects persisting beyond the immediate dosing period. A 1984 review in European Neurology described DSIP as a “sleep-promoting substance rather than a sedative,” noting a modulating effect on sleep-wake function with greater activity in cases where sleep was already disturbed and minimal effects in healthy subjects.
Multiple studies showed DSIP did not need to be given immediately before sleep. A dose administered during the day still produced improved sleep the following night and for several nights afterward, suggesting DSIP modulates circadian sleep pressure and does not directly induce sedation. Repeated administrations showed a cumulative effect, with normalisation of sleep architecture after four doses.
The most rigorous test was the 1992 double-blind study by Bes and colleagues in Neuropsychobiology. Sixteen chronic insomniacs were studied over five consecutive laboratory nights. The DSIP group received 25 nmol/kg intravenously on three consecutive afternoons. Objective polysomnography showed higher sleep efficiency and shorter sleep latency compared to placebo. However, the authors concluded the effects were “weak” and could partly reflect incidental change in the placebo group. Subjective sleep quality showed no significant change.
Evidence tier: Limited human data. All clinical sleep studies were conducted in the 1980s-1990s with small sample sizes. The best-designed trial (Bes 1992, n=16) found only weak effects. No study meets modern regulatory trial standards. The sleep-modulating hypothesis is plausible but not robustly demonstrated in controlled human research.
Opioid and alcohol withdrawal
The opioid receptor hypothesis led to two key human studies, both published in 1983-1984. Dick and colleagues (1984, European Neurology) administered DSIP intravenously to 107 inpatients presenting with alcohol (n=47) or opiate (n=60) withdrawal symptoms at a Swiss psychiatric facility. Assessment was based on clinical evaluation by physicians and nursing staff. After excluding patients who did not meet evaluation criteria, clinical symptoms of withdrawal disappeared or “improved markedly and rapidly” in 97% of evaluable alcoholic patients and 87% of opiate-dependent patients. Side effects were limited to headaches in a small number of participants.
A related study by Larbig and colleagues (1983, published as a 1984 paper in Neuropsychobiology) reported similar findings in 67 patients presenting with alcohol (n=28) or opiate (n=39) withdrawal. Of 49 evaluable patients, 48 showed beneficial effects with immediate onset and “good and lasting suspension of somatic symptoms and signs.” Anxiety resolved more slowly, within hours.
Evidence tier: Preliminary human data, high risk of bias. Both withdrawal studies were open-label with physician-assessed outcomes – no placebo control, no blinding, no standardised outcome measures. The response rates are striking (87-97%) but impossible to separate from placebo effects and the natural time-course of withdrawal. These studies would not meet current standards for any regulatory filing, which is precisely why the PCAC review matters.
Narcolepsy
Schneider-Helmert (1984, European Neurology) administered repeated DSIP injections to a single 35-year-old male narcoleptic. DSIP reduced the frequency of daytime sleep attacks, increased activity, alertness, and performance during waking hours, and compressed the nocturnal sleep period with enhancement of REM sleep. The author attributed the effects to DSIP’s accentuation of circadian and ultradian rhythms.
Evidence tier: Case report only. A single patient, uncontrolled, from 1984. This represents the lowest possible evidence tier and cannot support any efficacy conclusion. Its presence as a nominated PCAC indication likely reflects unmet clinical need in narcolepsy rather than the strength of existing evidence.
Other preclinical findings
| Area | Finding | Species | Tier |
|---|---|---|---|
| Stress response | Increased hypothalamic substance P, reduced stress markers (Salieva 1992) | Rat | Preclinical |
| Anticonvulsant | Prevented convulsive onset from GABA-A antagonists (Shandra 1993) | Rat | Preclinical |
| Antioxidant | Activated endogenous antioxidant mechanisms (Bondarenko 2011) | Rat | Preclinical |
| Anti-oedema | Antiedematic effect via GABAergic activation and monoamine inhibition (Platonov 1992) | Rat | Preclinical |
| Geroprotective | Slowed age-related oestrous decline, reduced chromosome aberrations by 22.6%, increased maximum lifespan by 24.1% | Mouse | Preclinical |
| Neuroprotection | DSIP-like KND peptide reduced brain infarction (Tukhovskaya 2025) | Mouse/Rat | Preclinical (analogue) |
The bottom line: the human evidence for DSIP is thin and old. The most frequently cited findings – dramatic withdrawal improvement and sleep modulation – come from uncontrolled or weakly controlled studies conducted 40 years ago. None has been replicated. The preclinical profile is broader and more interesting, but no animal finding has been validated in a modern human trial.
The “Unresolved Riddle” Problem
DSIP’s scientific story is unusual because the compound’s own name may be misleading. The 2006 review by Kovalzon and Strekalova in the Journal of Neurochemistry, titled “Delta sleep-inducing peptide: a still unresolved riddle,” laid out the core problem. Multiple studies failed to confirm DSIP’s sleep-promoting properties after either intraventricular or systemic administration. Some found only minor effects. At least one reported sleep impairment instead of the expected improvement.
Kovalzon and Strekalova raised a deeper concern: whether the synthesised DSIP used in biological investigations is truly identical to the natural substance originally isolated from rabbit dialysate. The DSIP gene has never been identified. There is doubt about whether the nonapeptide sequence isolated in 1977 is the complete active molecule or a fragment of a larger, still-unidentified endogenous compound. The scepticism was increased by contradictory results in the 1,500+ published studies on DSIP, which Kovalzon estimated had accumulated by the mid-2000s.
This matters for how you interpret the PCAC review. The FDA is evaluating emideltide – the synthetic nonapeptide – for three specific indications. But the underlying science cannot confidently explain how DSIP produces its observed effects, or even confirm that the synthetic version fully recapitulates the activity of the endogenous substance.
The DSIP-Depression Connection: An Overlooked Research Thread
One of the least-discussed aspects of DSIP research is a body of work from Lund University in Sweden, led by Anders Bjartell and colleagues, that links DSIP-like immunoreactivity (DSIP-LI) to depression, suicidal behaviour, and hypothalamic-pituitary-adrenal (HPA) axis regulation. This research thread has been largely ignored by the biohacker and peptide therapy communities, but it is directly relevant to understanding what DSIP actually does in the human body.
Bjartell’s immunohistochemical work in the late 1980s demonstrated that DSIP-like immunoreactivity is present in pituitary ACTH/MSH-producing cells and adrenal medullary cells – placing DSIP within the HPA axis and not solely in sleep-related circuits. A separate Bjartell study mapped DSIP-LI distribution in the human gut, finding it co-localised with known peptide hormones across multiple gastrointestinal regions, with the highest concentrations found in human specimens compared to pig and rat.
The clinical relevance emerged in a 1998 study published in Biological Psychiatry. Researchers measured plasma DSIP-LI levels in 34 suicide attempters with major depressive disorder (MDD) and matched healthy controls, alongside dexamethasone suppression testing. DSIP-LI levels were significantly elevated in MDD patients (p < .005). In healthy controls, there was a significant correlation between pre-dexamethasone cortisol and pre-dexamethasone DSIP-LI levels, suggesting DSIP participates in glucocorticoid feedback. Post-dexamethasone, DSIP-LI levels moved in opposite directions depending on baseline: they increased in subjects with initially low levels and decreased in those with initially high levels.
A related study by Westrin and colleagues found decreased plasma neuropeptide Y, decreased plasma corticotropin-releasing hormone, and increased plasma DSIP in suicide attempters with mood disorders. Taken together, this body of work suggests that DSIP is not simply a “sleep peptide” but an active participant in the stress-response system whose levels change in clinically meaningful ways during psychiatric crisis.
Why this matters: the Bjartell programme provides the strongest evidence that endogenous DSIP functions as part of the HPA axis stress-response system, not primarily as a sleep factor. This reframing has implications for the PCAC review: if DSIP’s primary physiological role involves stress and neuroendocrine regulation, its potential in opioid withdrawal may be more biologically grounded than its potential in insomnia – even though insomnia is the indication for which it was named.
An important caveat applies. As the Lund group themselves noted, the nature of DSIP-like immunoreactivity in humans is not fully characterised. The antibodies used in these studies may detect not only the synthetic nonapeptide but also structurally related endogenous peptides or fragments. This circles back to the Kovalzon riddle: the “DSIP” measured in plasma may not be identical to the synthetic compound being reviewed by the PCAC.
The bottom line: the Swedish DSIP-LI research provides a compelling alternative framework for understanding the compound – one centred on HPA axis regulation and stress response rather than sleep induction. No peptide content site currently covers this research thread, yet it may be the most clinically relevant body of DSIP evidence outside the withdrawal studies.
Safety Profile
Across the available clinical and preclinical literature, DSIP’s safety record is unusually clean for a compound with such limited formal study. Pollard and Pomfrett described DSIP as “incredibly safe” in their 2001 editorial, noting that no dose had ever killed an animal subject and that no significant side effects beyond transient headache, nausea, and vertigo had been reported in humans.
Reported adverse effects across all human studies are limited to transient headache, mild nausea, and occasional vertigo. No sedation, no hormonal suppression, no dependence, and no withdrawal effects have been documented. This is consistent with the compound’s profile as a sleep-modulating agent, not a sedative.
Important limitation: The total number of humans who have received DSIP in documented studies is small – likely fewer than 300 across all published literature. Safety data from small, short-duration studies conducted decades ago cannot substitute for the pharmacovigilance that comes with large-scale, monitored clinical use. The absence of reported serious adverse events may simply reflect the limited exposure instead of genuine safety.
Regulatory Status
| Jurisdiction | Status |
|---|---|
| United States (FDA) | Not approved for any indication. Category 2 removed April 15, 2026. PCAC review scheduled July 24, 2026 (Day 2) for three indications: opioid withdrawal, chronic insomnia, narcolepsy. Docket FDA-2025-N-6895. Public comment deadline July 9, 2026. |
| United Kingdom (MHRA) | Not licensed. No marketing authorisation. |
| Australia (TGA) | Not approved. Not scheduled. |
| Russia | Not an approved pharmaceutical product. |
| WADA | Not individually listed. May fall under S0 blanket prohibition as a non-approved pharmacological substance with no current therapeutic approval in any country. |
DSIP occupies an unusual regulatory position. Unlike Semax and Selank, which are approved pharmaceuticals in Russia, DSIP has never been approved as a drug by any regulatory authority anywhere in the world. Its PCAC nomination is being evaluated purely on the basis of published literature and nominator-submitted data, not on an existing track record as an approved pharmaceutical.
For an overview of how different countries regulate peptide compounds, see our guides for the US, the UK and Australia.
Why DSIP Has Not Been Developed as a Drug
Several structural barriers have prevented DSIP from advancing through conventional pharmaceutical development. The rapid enzymatic degradation (approximately 15-minute half-life) means any therapeutic application would require either frequent dosing, modified delivery systems, or structural analogues resistant to breakdown. The 1986 intraventricular study in rats found that DSIP itself did not increase sleep when injected directly into the brain, likely due to rapid metabolism, though two of its synthetic analogues did induce sleep.
The absence of a defined receptor target makes it difficult to design a drug development programme around DSIP. Without knowing exactly where it binds and how it produces its effects, the path from preclinical to clinical is harder to map. The pleiotropic activity profile – sleep, stress, withdrawal, endocrine modulation, antioxidant – is scientifically interesting but commercially problematic. Pharmaceutical development favours compounds with defined mechanisms and clear target indications.
The bottom line: DSIP has been studied for nearly fifty years without progressing past small, preliminary human trials. The 2026 PCAC review represents the closest it has ever come to a formal regulatory evaluation, and the outcome will depend on whether the nominator can present a convincing case from the available literature.
How DSIP Fits Within the Neuropeptide Landscape
DSIP is distinct from the other neuropeptides in this cluster. Where Semax and Selank are products of a deliberate Russian peptide engineering programme and share a common stabilisation design, DSIP was discovered through an entirely different route – a Swiss behavioural neuroscience experiment that identified an endogenous substance through its observable effects. DSIP has no structural relationship to the ACTH or tuftsin lineages. It was never part of a national pharmaceutical programme and has no manufacturer in the way that Peptogen JSC produces Semax.
For the full cluster overview and compound comparison table, see the nootropic and neuropeptide compounds hub.
Sourcing and Quality
DSIP is not approved as a pharmaceutical in any country and has no regulated supply chain. Anyone sourcing DSIP obtains it from research chemical suppliers, which means the standard quality verification applies: third-party certificates of analysis showing identity confirmation (mass spectrometry), purity (HPLC, target above 98%), and the absence of endotoxins and heavy metals. For how to evaluate these documents, see our guide to reading a certificate of analysis.
The bottom line: there is no approved pharmaceutical-grade DSIP product anywhere in the world. All supply is research-grade, which means quality varies significantly between suppliers.
Medical disclaimer: DSIP (emideltide) is not approved by the FDA, EMA, MHRA, or TGA for any therapeutic indication. Nothing on this page constitutes medical advice or a recommendation for use. All information is drawn from published research and regulatory filings and is presented for educational purposes.