DSIP vs Selank
Delta sleep-inducing peptide is the nonapeptide Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu, isolated in 1977 from the cerebral venous blood of sleep-induced rabbits and still without an identified gene, precursor protein or receptor. Selank is the synthetic heptapeptide Thr-Lys-Pro-Arg-Pro-Gly-Pro, derived from the immunomodulatory tetrapeptide tuftsin and developed at the Institute of Molecular Genetics in Moscow as a peptide anxiolytic. Both are sold as Russian-tradition research peptides and are commonly stacked in vendor material, one framed as a sleep agent and the other as an anxiolytic. No published study has administered them together, compared them, or measured one against the other. The four publications that engage both are reviews and national development surveys that list them as separate entries in the same peptide catalogue. Any comparison therefore rests on two independent literatures separated by decades, species, endpoints and research groups.
No study has compared them directly.
Everything below is drawn from separate studies that used different models, endpoints and species. That is a real limit on what can be concluded, not a formality.
No study has administered delta sleep-inducing peptide and Selank in the same experiment, and none has compared their effects on sleep, anxiety or any other endpoint. Searches of PubMed and Europe PMC returned four publications that engage both compounds, all of them reviews or classification papers. A 2022 survey of Russian peptide biopharmaceutical development listed Selank as an anxiolytic and Deltaran, whose sequence is that of delta sleep-inducing peptide, as a stress protector, as two separate entries in one table of original national peptide preparations. A 2026 review of therapeutic peptides in aesthetic, metabolic and endocrine conditions grouped them in a single neuromodulator category alongside Semax and Cerebrolysin, describing DSIP as an injected nonapeptide with a half-life of minutes and Selank as an intranasal tuftsin fragment. A 2026 orthopaedic review assigned them to different functional groups, delta sleep-inducing peptide to sleep and recovery agents and Selank to neuroactive peptides, and stated plainly that clinical trials are lacking for the class.
The 4 publications that cover both
- 01Review2026
Therapeutic Peptides in Aesthetic, Metabolic and Endocrine Conditions: Effects, Safety, Clinical Applications, and Future Perspectives
Renke G, Chinellato L · International Journal of Molecular Sciences · narrative review of 106 articles, prioritising systematic reviews, meta-analyses and randomised controlled trials
Both compounds were placed in one neuromodulator category alongside Semax and Cerebrolysin. Delta sleep-inducing peptide was described as a nine-amino-acid peptide found in the hypothalamus and cerebrospinal fluid, named for inducing slow-wave sleep in rabbits, given by injection and eliminated with a half-life of minutes. Selank was described as a tuftsin fragment with anxiolytic and nootropic properties reported without significant sedation, and as one of the peptides formulated for intranasal delivery. Neither was administered and no comparison between them was drawn.
- 02Review2022
Development of Peptide Biopharmaceuticals in Russia
Deigin VI, et al. · Pharmaceutics · review of the history, chemistry and clinical-pharmacological classification of original peptide drugs developed in Russia
The review's table of original Russian peptide preparations listed Selank, given as L-threonyl-L-lysyl-L-prolyl-L-arginyl-L-prolylglycyl-L-proline, in the anxiolytic class, and Deltaran, given as tryptophanyl-alanyl-glycyl-glycyl-aspartyl-alanyl-seryl-glycyl-glutamic acid and therefore the delta sleep-inducing peptide sequence, as a stress protector used in alcohol addiction. The two appeared as separate entries within one national development programme, and no experiment involving both was reported.
- 03Review2026
Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions
Rahman OF, Lee SJ, Seeds WA · Journal of the American Academy of Orthopaedic Surgeons Global Research & Reviews · narrative review of therapeutic peptides in orthopaedic recovery
Delta sleep-inducing peptide was tabulated among sleep and recovery peptides, with hypothalamic growth hormone release and mitochondrial biogenesis given as its proposed pathways, while Selank was tabulated among neuroactive peptides acting through BDNF, serotonin and dopamine signalling and TrkB. The review described Selank as approved in Russia for the treatment of anxiety, and stated that although preclinical studies are promising there is a current lack of clinical trials across the peptides covered.
- 04Animal in vivo1998· Russian
[Peptide correction of disturbed relations in the central nervous system]
Popova NS, Kachalova LM, Ustinovskaia OV · Bulletin of Experimental Biology and Medicine (Biulleten' eksperimental'noi biologii i meditsiny) · cats and dogs; penicillin- and levodopa-induced disturbance of brain activity assessed by electroencephalography, evoked potentials, and brain acetylcholinesterase and monoamine oxidase measurement
The record is indexed as a comparative study whose substances include delta sleep-inducing peptide and tuftsin, the tetrapeptide from which Selank was subsequently derived; Selank itself is not among the indexed compounds. The PubMed record carries no abstract, so what was observed cannot be summarised from it. It is included here because it is the only located experiment that administered delta sleep-inducing peptide alongside a peptide of the tuftsin family.
Side by side.
| DSIP | Selank | |
|---|---|---|
| Evidence maturity | Preclinical only | Early clinical |
| Studies cited here | 17 | 15 |
| Published 2023 or later | 1 | 0 |
| Newest paper | 2024 | 2022 |
| Sequence and origin | A nonapeptide, Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu, isolated in 1977 from the cerebral venous blood of rabbits in induced sleep. Its status as an endogenous sleep factor is disputed in the primary literature rather than settled. | A synthetic heptapeptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, built from the immunomodulatory tetrapeptide tuftsin with a Pro-Gly-Pro extension, developed at the Institute of Molecular Genetics in Moscow. Its parent peptide is a defined fragment of immunoglobulin G heavy chain. |
| Mechanism and molecular target as described in the literature | No gene, precursor protein or receptor has ever been identified for it, which a 2006 critical mini-review in the Journal of Neurochemistry described as leaving the sleep-factor hypothesis poorly documented and weak. Proposed actions are broad: stress and HPA axis modulation, antioxidant and geroprotective effects, and blood-brain barrier transport. | A specific receptor has also not been identified, but three concrete mechanisms have been measured: dose-dependent inhibition of plasma enkephalin-degrading enzymes, altered expression of GABAergic neurotransmission genes in rat frontal cortex and in a human neuroblastoma line, and changes in hippocampal BDNF after intranasal administration. |
| Size and composition of the evidence base | Seventeen studies in this library: eight animal in vivo, seven human clinical and two reviews. The human work is concentrated in the 1980s and early 1990s, and the recent additions are rodent stroke, stress and drug-delivery studies rather than sleep trials. | Fifteen studies in this library: five human clinical, five animal in vivo, three in vitro and two reviews. Almost the entire corpus originates from a small group of Russian laboratories, and independent Western replication is absent. |
| Best-characterised finding | A 1988 rat study in the Proceedings of the National Academy of Sciences reported evidence linking the peptide to slow-wave sleep and sleep-associated growth hormone release; it remains the most frequently cited mechanistic basis for the sleep claims, and it is an animal immunoneutralisation and administration study. | Inhibition of enzymatic hydrolysis of plasma enkephalin, reported as dose-dependent and more potent than bacitracin or puromycin, with shortened enkephalin half-life observed at baseline in patients with generalised anxiety. This links a measured biochemical action to a clinical population. |
| Human data | Older and inconsistent. A double-blind polysomnography trial in chronic insomnia found only weak effects, partly attributable to change in the placebo group, and its authors concluded short-term treatment was unlikely to be of major therapeutic benefit. A randomised trial during isoflurane anaesthesia found the peptide lightened rather than deepened anaesthetic depth, contrary to the hypothesis. Plasma measurements correlated negatively with slow-wave and REM sleep. | Comparative rather than placebo-controlled. Russian trials in generalised anxiety disorder, neurasthenia and phobic-anxiety and somatoform disorders compared the peptide with medazepam or phenazepam, or added it to phenazepam, and reported comparable anxiolytic effect with fewer benzodiazepine-related adverse effects. One placebo-controlled resting-state fMRI study in healthy volunteers reported connectivity changes. |
| Evidence maturity and regulatory status | Preclinical only. No modern randomised controlled trial exists, no pharmacokinetic characterisation exists for non-intravenous routes, and no medicines regulator has approved it in any jurisdiction. | Early clinical. Human trials exist but no Phase III programme has been conducted, and no randomised placebo-controlled trial has been published outside Russia. A 2026 orthopaedic review described the peptide as approved in Russia for the treatment of anxiety. |
| Recency of primary research | Thin but continuing. The newest primary study is a 2024 mouse experiment on a recombinant fusion peptide expressed in Pichia pastoris, and only one of seventeen entries dates from 2023 or later. | Stalled. The most recent primary research article indexed in PubMed is a 2022 rat morphine withdrawal study, and no entry in this library is newer than that. |
| Basis of most marketing claims | Extrapolation from the 1977 discovery narrative and rabbit and rat sleep work to subcutaneous use in humans, despite the human trials having used intravenous administration and having produced inconsistent sleep outcomes. | Extrapolation from Russian comparative psychiatric trials, mostly published in one journal and unavailable in full outside Russian-language sources, to cognitive and stress effects in healthy adults, an application no trial has tested. |
And what it does not.
The combined evidence supports no ranking of these two peptides, because nothing has ever compared them. What it does support is a description of two literatures with opposite shapes. Delta sleep-inducing peptide has almost fifty years of study and still no identified gene, precursor or receptor, human trials that are small, old, intravenous and inconsistent, and one randomised anaesthesia study whose result ran against the sleep hypothesis. Selank has a smaller and more recent literature with clearer measured mechanisms, and human trials that reported anxiolytic effect comparable to benzodiazepines with fewer adverse effects, but those trials were comparative rather than placebo-controlled, came from a narrow group of Russian laboratories, and have not been replicated independently. Neither compound has a randomised placebo-controlled trial conducted to Western regulatory standards, neither has pharmacokinetic characterisation for the routes by which they are sold, and no study has examined whether using them together changes what either does.
Common questions.
- Has any study looked at DSIP and Selank taken together?
No. Searches of PubMed and Europe PMC found no experiment, in any species, that administered both compounds, and no clinical or preclinical work on combining them. The four publications naming both are reviews that catalogue Russian or research-market peptides and list the two as separate entries, sometimes in different functional groups. Claims about a sleep-and-anxiety stack are therefore not drawn from published data on the combination; nothing has measured whether one alters the effect, absorption or duration of the other.
- Why is delta sleep-inducing peptide still described as unresolved after decades of work?
Because the basic molecular biology was never established. No DSIP gene, precursor protein or receptor has been isolated, which means there is no confirmed pathway through which the peptide would act and no way to demonstrate target engagement. A 2006 mini-review in the Journal of Neurochemistry concluded that the sleep-factor hypothesis was poorly documented and weak, and noted that certain synthetic analogues, but not the peptide itself, promoted slow-wave sleep in rabbits and rats.
- Do the Selank anxiety trials show it works as well as a benzodiazepine?
They report comparable effect, but the design limits what that means. The trials were active-comparator studies against medazepam or phenazepam, or add-on studies alongside phenazepam, rather than placebo-controlled trials. Without a placebo arm, a comparable score on the Hamilton or Zung scales does not separate drug effect from natural improvement and expectation. The trials were also conducted by a small number of Russian groups, published largely in one journal, and have not been replicated elsewhere.
- What did the human sleep studies of DSIP actually measure?
A double-blind matched-pairs trial in chronic insomnia used polysomnography and found higher sleep efficiency and shorter sleep latency, but the effects were weak and partly attributable to change in the placebo group, and the authors concluded short-term treatment was unlikely to be of major therapeutic benefit. Separate work found plasma levels correlating positively with body temperature and negatively with REM and slow-wave sleep, a pattern opposite to that expected of a circulating sleep-promoting factor.
- Is either peptide still being researched?
Both have slowed, and Selank has slowed further. The most recent primary Selank research article indexed in PubMed is a 2022 rat morphine withdrawal study, with nothing newer since. Delta sleep-inducing peptide has one 2024 entry, a mouse study of a recombinant fusion peptide produced in Pichia pastoris and tested in a chemically induced insomnia model. In both cases the recent output is animal or laboratory work, not clinical trials, and no registered modern trial of either was located.
For research purposes only. Not for human consumption, diagnosis, treatment, or prevention of any condition. Nothing on this page is medical advice, and no comparison here should be read as a recommendation of either compound.