What is inside
“Relaxation” is a sales name. Sellers use it for a mixture sold as a “peptide” sleep blend. But most of what is inside is not a peptide. GABA is a single amino acid that acts as the brain’s main calming signal. Melatonin is a hormone the brain makes at night. Arginine and glutamine are ordinary amino acids from protein. None of these is a regulatory peptide. Some sellers add one real peptide: DSIP, a nine-amino-acid chain studied for sleep in the 1980s, or Selank, a seven-amino-acid chain registered in Russia for anxiety.
There is no official recipe. Each seller decides which of these go in and how much of each. Nothing is standardised. No drug standard or regulator defines the name. So the label is the only description of what is inside. DSIP and Selank have their own pages on this site. The next sections sum up each ingredient.
The product is a physical mixture of small molecules with, in some versions, one synthetic peptide. Gamma-aminobutyric acid is a non-proteinogenic amino acid and the principal inhibitory neurotransmitter of the mammalian brain; melatonin is the pineal indoleamine hormone; L-arginine and L-glutamine are proteinogenic amino acids, the latter the most abundant free amino acid in plasma. The optional peptides are emideltide, DSIP (Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu, 848.8 g/mol), and Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro, 751.9 g/mol, usually as the acetate). The marketing category “peptide sleep blend” therefore describes a product that may contain no peptide at all.
No reference standard exists for the mixture. Per-ingredient amounts and ratios are set by each seller and are not standardised, and no compatibility or stability data for peptides stored with free amino acids in solution were found. Pharmacokinetic interactions are unstudied: oral GABA is absorbed with a blood peak at about 30 minutes (Yamatsu et al. 2016), melatonin trials used 0.15-12 mg/day, and DSIP has only intravenous human data, so route-specific exposure for a combined injectable product is unknown.
Who made it and when
No one invented this blend. It has no inventor, developer or date. Its ingredients have separate histories. Melatonin has been studied for sleep for decades and is approved as a prescription medicine in Europe: Circadin, a 2 mg slow-release tablet, was authorised in 2007 for poor-quality sleep in people aged 55 and over. In the United States melatonin is sold as a dietary supplement instead. GABA is sold as a supplement too. Arginine and glutamine are both ingredients of approved medicines, for other uses.
DSIP was found in rabbits in Switzerland in 1977 and tested in small sleep studies in the 1980s. Selank was developed in Moscow and registered in Russia as nasal drops for anxiety. The idea of putting all of these in one vial comes from sellers, not from any research group.
No originator, patent or investigational programme exists for the combination. Component histories: melatonin, as Circadin 2 mg prolonged-release tablets, received European marketing authorisation on 2007-06-29 as prescription-only monotherapy for short-term treatment of primary insomnia characterised by poor quality of sleep in patients aged 55 or over; in the US it is regulated as a dietary supplement and, for compounding, sits in 503A Category 1. L-arginine hydrochloride has been an approved intravenous diagnostic agent (R-Gene 10) for stimulating pituitary growth hormone release, and L-glutamine was approved in 2017 as Endari oral powder to reduce acute complications of sickle cell disease.
DSIP (emideltide) was isolated by Schoenenberger and Monnier in Basel in 1977 and studied in small intravenous sleep studies in the 1980s; Selank was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences and registered in Russia as 0.15% nasal drops. Both were nominated for the 503A bulks list, placed in Category 2 in 2023 and later withdrawn by the nominators; DSIP was reviewed by FDA’s advisory committee on 2026-07-24. Full detail is on each peptide’s page.
What the data say
No study has tested this mixture. The ingredients have very different amounts of evidence. Melatonin has the most. A 2013 analysis pooled 19 placebo-controlled trials with 1,683 people. Melatonin helped people fall asleep about 7 minutes sooner and sleep about 8 minutes longer. Sleep quality improved a little. The authors called the effects modest.
GABA has much less. A 2020 review found 14 placebo-controlled studies of oral GABA. It concluded there is limited evidence for stress and very limited evidence for sleep. One small company-run study found GABA shortened the time to fall asleep. Arginine and glutamine have no sleep trials at all. One Chinese trial gave glutamine with three other supplements to people withdrawing from heroin, and insomnia scores improved, but glutamine’s own role cannot be separated. DSIP was tested in small 1980s studies, given into a vein; one double-blind study found the sleep changes were of little clinical significance. Selank’s human studies were for anxiety, with no placebo group.
No trial of the combination was identified. Melatonin: Ferracioli-Oda et al. (2013) pooled 19 randomised placebo-controlled trials (n = 1,683) in primary sleep disorders and found reduced sleep-onset latency (weighted mean difference 7.06 min, 95% CI 4.37-9.75), increased total sleep time (8.25 min, 95% CI 1.74-14.75) and improved sleep quality (standardised mean difference 0.22, 95% CI 0.12-0.32), with larger latency effects at higher doses and longer durations; the authors describe the absolute benefit as smaller than that of other hypnotics.
GABA: Hepsomali et al. (2020) systematically reviewed 14 placebo-controlled trials of natural or biosynthetic oral GABA and concluded there is limited evidence for stress and very limited evidence for sleep benefits. Yamatsu et al. (2016), authors employed by a GABA manufacturer, reported in a randomised single-blind placebo-controlled crossover that oral GABA shortened EEG-measured sleep latency and increased non-REM sleep time, with peak blood GABA at 30 minutes. Arginine and glutamine: no randomised trial with a sleep endpoint was identified for either amino acid alone; Chen et al. (2012) gave tyrosine, lecithin, L-glutamine and 5-HTP together to 41 detoxified heroin users versus 42 on placebo in a cluster-randomised trial and reported improved insomnia and withdrawal scores, a combination result that cannot be attributed to glutamine. DSIP: Monti et al. (1987), a double-blind intravenous crossover at 25 nmol/kg on four nights, found no significant differences from placebo in awakenings or latency and judged the improvement of little clinical significance. Selank: Zozulia et al. (2008) compared Selank with medazepam in 62 patients with generalised anxiety disorder or neurasthenia without a placebo arm.
Ingredient: GABA
GABA (gamma-aminobutyric acid) is the brain’s main “slow down” signal. Nerve cells release it to quiet other nerve cells. Many sleeping pills work by boosting GABA’s effect. That is the logic of putting GABA itself in a sleep product. The catch is that GABA swallowed or injected must reach the brain, and whether it crosses from blood into brain in useful amounts is still debated.
The human evidence is thin. A 2020 review found 14 placebo-controlled studies of GABA taken by mouth. Its verdict: limited evidence for stress, very limited evidence for sleep. One small Japanese study, run by a GABA maker, found people fell asleep faster after GABA. GABA is sold as a dietary supplement in the United States. For pharmacy compounding, the FDA lists it in Category 3, meaning it was nominated without enough supporting information.
GABA is the principal inhibitory neurotransmitter of the mammalian central nervous system, acting at ionotropic GABA-A and metabotropic GABA-B receptors; benzodiazepines and Z-drugs act as positive modulators at GABA-A. Exogenous GABA’s central penetration is unresolved, and Hepsomali et al. (2020) note that results on oral intake are mixed despite GABA’s well-established central role.
Their systematic review, restricted to placebo-controlled human trials of natural or biosynthetic oral GABA published to February 2020, included 14 studies and concluded that more studies are needed before inferences can be made, with limited evidence for stress and very limited evidence for sleep. The one dedicated sleep study, Yamatsu et al. (2016), was a randomised single-blind crossover with EEG endpoints reporting shorter sleep latency and more non-REM sleep, and rapid absorption with peak blood GABA at 30 minutes; all authors were employees of the manufacturer. No trial of injected GABA for sleep was found. GABA is not a component of an approved drug and sits in 503A Category 3 (nominated without adequate support) on FDA’s list updated 2026-05-14.
Ingredient: Melatonin
Melatonin is a hormone made by the pineal gland in the brain. Levels rise in darkness and tell the body it is night. Taken as a supplement, it nudges the body clock and can help people fall asleep sooner. Across 19 trials, the gain was about 7 minutes to fall asleep and 8 minutes of extra sleep. That is real but modest.
Side effects in trials were uncommon and mostly mild. A review of 37 trials found daytime sleepiness in 1.66% of people, headache and dizziness in 0.74% each, and a low body temperature in 0.62%. Long-term safety is not well studied. The NIH says melatonin may stay active longer in older people and cause daytime drowsiness. People with epilepsy or on blood thinners should be under a doctor’s care if they use it. In the United States melatonin is a dietary supplement. In Europe it is a prescription drug (Circadin). For compounding, the FDA lists it as “under evaluation” (Category 1).
Melatonin (N-acetyl-5-methoxytryptamine) is secreted nocturnally by the pineal gland and acts at MT1 and MT2 receptors to signal darkness and shift circadian phase. In the Ferracioli-Oda meta-analysis, effects on latency and total sleep time increased with dose and duration, while sleep-quality gains did not; the authors judged the effects modest and not dissipating with continued use.
Safety: Besag et al. (2019) reviewed 37 randomised placebo-controlled trials with daily doses of 0.15-12 mg and follow-up of up to 29 weeks (most 4 weeks or less); the most frequent adverse events were daytime sleepiness (1.66%), headache (0.74%), other sleep-related events (0.74%), dizziness (0.74%) and hypothermia (0.62%), with few serious events, and they stressed the scarcity of long-term data and of evidence in at-risk groups. NIH NCCIH adds that melatonin may remain active longer in older adults, causing daytime drowsiness, advises supervision for people with epilepsy or on anticoagulants, and cites a CDC estimate of 11,000 emergency visits for unsupervised ingestion by children aged 5 and under in 2019-2022. Regulatory status differs by region: a dietary supplement in the US, prescription-only Circadin 2 mg prolonged-release in the EU (authorised 2007-06-29 for primary insomnia in patients aged 55 or over), and 503A Category 1 for US compounding.
Ingredient: Arginine
Arginine is an amino acid found in protein foods. The body also makes it. It is the raw material for nitric oxide, a signal that widens blood vessels. Given into a vein in large amounts, it makes the pituitary gland release growth hormone. That is why an arginine injection, R-Gene 10, is an approved diagnostic test for growth hormone problems. The growth hormone link is probably why sellers put it in a “sleep” product, since growth hormone is released during deep sleep. But no study shows that arginine improves sleep.
The R-Gene 10 label lists nausea, vomiting, headache, flushing, numbness and vein irritation in about 3% of patients. If the solution leaks out of the vein, it can burn the skin and cause tissue death. Overdoses in children have caused death. These are risks of a concentrated intravenous product, not of dietary arginine, but they show the amino acid is not inert.
L-arginine is a semi-essential amino acid and the substrate of nitric oxide synthase. Its pharmacological use is diagnostic: R-Gene 10 (L-arginine hydrochloride 10% for intravenous infusion) is indicated as an intravenous stimulant to the pituitary for release of growth hormone, and its label states that infusion often induces a pronounced rise in plasma growth hormone in subjects with intact pituitary function, with the response diminished or absent in pituitary impairment.
No randomised trial of arginine, alone, with a sleep endpoint was identified, and the R-Gene 10 label mentions sleep only in requiring a normal night’s sleep before the test. The label’s safety profile is that of a hypertonic intravenous solution: nausea, vomiting, headache, flushing, numbness and local venous irritation in about 3% of patients; post-marketing extravasation causing burn-like reactions and skin necrosis requiring surgery; and paediatric overdoses causing hyperchloremic metabolic acidosis, cerebral edema and death. The only contraindication is hypersensitivity to an ingredient. As a component of an approved drug, L-arginine hydrochloride meets a 503A eligibility criterion on its own; it does not appear on FDA’s category lists.
Ingredient: Glutamine
Glutamine is the most common amino acid in the blood. Muscles make it and gut and immune cells use it as fuel. It is sold as a sports supplement. It is also an approved medicine: Endari, a glutamine powder taken by mouth, was approved in 2017 to reduce painful crises in sickle cell disease. In its main trial of 230 patients, people on glutamine had a median of 3 crises in 48 weeks against 4 on placebo.
Nothing in that connects to sleep. No trial of glutamine for sleep was found. One trial gave glutamine together with three other supplements to people coming off heroin, and their insomnia scores improved, but the mix makes it impossible to say what glutamine did. The Endari label lists constipation, nausea and headache as the most common side effects, and no contraindications. A related compound, alanyl-glutamine, is “under evaluation” for compounding.
L-glutamine is a conditionally essential amino acid, the most abundant free amino acid in plasma, and a major fuel for enterocytes and lymphocytes. Its approved use is unrelated to sleep: Endari (L-glutamine oral powder, initial US approval 2017) is indicated to reduce the acute complications of sickle cell disease in patients aged 5 years and older; in the pivotal 48-week trial of 230 patients with sickle cell anemia or sickle beta-zero-thalassemia, the median number of crises was 3 with Endari versus 4 with placebo.
No randomised trial of glutamine monotherapy with a sleep endpoint was identified. Chen et al. (2012) reported improved insomnia and withdrawal scores in 41 detoxified heroin users given tyrosine, lecithin, L-glutamine and 5-hydroxytryptophan versus 42 on placebo, a four-component intervention from which no glutamine-specific inference is possible. The Endari label’s most common adverse reactions are constipation (21%), nausea (19%), headache (18%), abdominal pain (17%), cough (16%), pain in extremity (13%), back pain (12%) and chest pain (12%), with no contraindications. As a component of an approved drug, L-glutamine meets a 503A eligibility criterion; the dipeptide alanyl-L-glutamine is separately in Category 1 on FDA’s list updated 2026-05-14.
Ingredient: DSIP (some versions)
DSIP stands for delta sleep-inducing peptide. It is a chain of nine amino acids. Swiss researchers found it in 1977 in the blood of rabbits kept asleep. When given back to rabbits, their brain waves shifted toward the slow waves of deep sleep. That gave it its name. No one has found a receptor for it, and it breaks down in the blood within minutes.
Human studies are old and small. They gave DSIP into a vein. In a double-blind study in adults with long-term insomnia, DSIP at 25 nmol/kg on four nights did not differ significantly from placebo in awakenings or time to fall asleep. The authors said the sleep changes had little clinical significance. No human study has tested DSIP under the skin, the route sellers describe. The FDA put DSIP in Category 2 (significant safety concerns) in 2023. The nominators later withdrew it, and an FDA advisory committee reviewed it for chronic insomnia and other uses in July 2026. It is not approved anywhere.
Emideltide (DSIP, Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu, C35H48N10O15, 848.8 g/mol) was isolated from the cerebral venous blood of rabbits in 1977 and named for the increase in delta-wave EEG activity after administration. No receptor has been identified and plasma half-life is measured in minutes.
The controlled human data are limited to intravenous studies from the 1980s. Monti et al. (1987) gave 25 nmol/kg or placebo intravenously on four nights in a double-blind crossover with polysomnography; nocturnal awakenings, NREM latency and waking time fell under DSIP but did not differ significantly from baseline or placebo, and the increase in total and NREM sleep time was confined to stage 2, with differences already present at baseline. FDA’s safety-risk page records that DSIP was placed in 503A Category 2 in 2023, citing immunogenicity concerns and a lack of safety data for the proposed route, and later withdrawn by the nominators; the Pharmacy Compounding Advisory Committee reviewed emideltide free base and acetate for opioid withdrawal, chronic insomnia and narcolepsy on 2026-07-24. Full detail, including the vote, is on the DSIP page.
Ingredient: Selank (some versions)
Selank is a lab-made chain of seven amino acids. Its first four copy tuftsin, a small immune signal. It was developed in Moscow and is registered in Russia as 0.15% nasal drops for anxiety. It is not approved in the United States or Europe.
Its human studies are small and Russian. In one, 62 adults with generalised anxiety disorder or neurasthenia got Selank nose drops or the drug medazepam. Anxiety fell about as much on Selank as on medazepam, and the authors reported an extra “anti-fatigue” effect. There was no placebo group. It has not been tested for sleep. The FDA placed selank acetate in Category 2 in 2023 and later removed it from that category, and its safety-risk page still lists the concerns raised: possible immune reactions and peptide impurities, and a lack of human safety data.
Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro, C33H57N11O9, 751.9 g/mol) is a synthetic analogue of tuftsin with a C-terminal Pro-Gly-Pro extension intended to slow degradation. Its registration is Russian, as 0.15% nasal drops. Zozulia et al. (2008) compared Selank (30 patients) with medazepam (32 patients) in 62 adults with generalised anxiety disorder or neurasthenia using Hamilton, Zung and CGI scales, reporting similar anxiolytic effects with additional antiasthenic and psychostimulant effects for Selank and a rise in serum leu-enkephalin half-life; the study had no placebo arm and randomisation and blinding are not described in the abstract.
No study of Selank with a sleep endpoint was identified, and no human pharmacokinetic study for any route. On FDA’s safety-risk page (updated 2026-04-22), selank acetate (TP-7) is listed among substances withdrawn from 503A Category 2, with the identified risks of immunogenicity for certain routes due to potential aggregation and peptide-related impurities. It is not on the 503A bulks list and is not a component of any approved drug.
Why researchers might study these together
The idea is to hit sleep from several sides at once. GABA is the brain’s calming signal. Melatonin tells the body it is night. Arginine can trigger growth hormone, which is normally released in deep sleep. Glutamine is the raw material the brain uses to make GABA. DSIP was named for deep-sleep brain waves. Selank is for anxiety, which keeps people awake. On paper, that is a story. In practice, it is a hypothesis that no one has tested.
The pieces do not fit as neatly as the story suggests. Glutamine is also turned into glutamate, the brain’s main “wake up” signal. Arginine’s growth hormone effect was shown with large doses into a vein, not with a sleep blend. Whether GABA reaches the brain at all is unsettled. And the only ingredient with solid sleep evidence, melatonin, works on its own. No study has compared the blend with melatonin alone, or with anything else.
The proposed rationale is multi-target sedation: GABA-A-mediated inhibition (GABA), circadian phase signalling at MT1/MT2 (melatonin), pituitary growth hormone release (arginine, via its diagnostic pharmacology), precursor supply for GABA synthesis via glutamate decarboxylase (glutamine), a putative slow-wave-sleep factor (DSIP) and anxiolysis (Selank). Each element derives from a separate literature, and none has been examined in combination.
Several assumptions are unsupported or contradictory. Glutamine is the precursor of both glutamate and GABA, so net effects on excitatory-inhibitory balance are not predictable. The growth hormone response to arginine is documented for 30 g intravenous infusions in a diagnostic setting, not for any sleep product. Exogenous GABA’s blood-brain-barrier penetration is unresolved, which is one reason oral GABA trials are mixed. DSIP has no human data by any route other than intravenous. Melatonin’s efficacy is established as monotherapy, and the combination has never been tested against melatonin alone, placebo or standard hypnotics. PubMed searches identified no preclinical or clinical study of GABA, melatonin, arginine or glutamine combined with DSIP or Selank, or of the four small molecules together, for sleep.
Regulatory picture
Approval: no regulator has approved this mixture. Its parts have different statuses. Melatonin is a dietary supplement in the United States and a prescription medicine in Europe. GABA is a supplement. Arginine and glutamine are ingredients of approved medicines, for other uses. DSIP and Selank are not approved anywhere in the West; Selank is registered in Russia.
Compounding (pharmacies mixing their own drugs): the FDA judges each ingredient on its own. Arginine and glutamine are parts of approved drugs, so pharmacies may use them. Melatonin is “under evaluation” (Category 1). GABA was nominated without enough support (Category 3). DSIP and Selank were placed in Category 2, the “significant safety concerns” group, in 2023, and later withdrawn by the people who nominated them. An FDA advisory committee reviewed DSIP for chronic insomnia and other uses in July 2026. The blend as a whole has no status of its own.
Enforcement: no FDA action naming this blend was found. Selling injectable versions of these ingredients as “research” products does not change their legal status as drugs.
Approval: none for the combination. Component status: melatonin is a dietary supplement in the US and prescription-only Circadin in the EU; GABA a dietary supplement; L-arginine hydrochloride and L-glutamine are active ingredients of the approved drugs R-Gene 10 and Endari; emideltide and Selank have no US or EU approval.
Compounding: under section 503A(b)(1)(A)(i), each bulk substance must have an applicable USP or NF monograph, be a component of an approved drug, or appear on the 503A bulks list in 21 CFR 216.23. Arginine and glutamine qualify as components of approved drugs. On FDA’s nominations list updated 2026-05-14, melatonin is in Category 1 (under evaluation, with enforcement discretion under the interim policy) and gamma-aminobutyric acid in Category 3. Emideltide and selank acetate were placed in Category 2 in 2023 and are listed on FDA’s safety-risk page (updated 2026-04-22) as withdrawn by their nominators, with the identified concerns of immunogenicity and absent safety data for the proposed routes; neither is on the bulks list. FDA’s Pharmacy Compounding Advisory Committee reviewed emideltide for opioid withdrawal, chronic insomnia and narcolepsy on 2026-07-24; the DSIP page records the vote, which is non-binding. A blend has no status of its own and inherits the least-established status of its components, so this article records compounding as unknown.
Enforcement: no warning letter or other action naming a relaxation or sleep blend was found in the sources reviewed.
