A few tiny randomized, placebo-controlled insomnia trials exist, mostly from the 1980s, but FDA's 2026 review judged the overall evidence insufficient and DSIP has never been approved[1,2].
A small peptide first found in rabbit blood and tested in tiny insomnia studies decades ago, with mixed results; FDA's 2026 review found the evidence insufficient.
Overview
Delta sleep-inducing peptide (DSIP, official name emideltide) is a nine-amino-acid peptide first found in blood draining from the brains of rabbits and later synthesized in 1976[1]. The name reflects what early researchers hoped it did: promote "delta" or slow-wave sleep, the deepest stage of non-dream sleep. Fifty years later, how it works, and whether it reliably does that in people, is still unsettled[1,2].
Human research is small, old and mixed. Several 1980s studies from a single investigator reported better sleep in people with insomnia, but most lacked a true placebo group. The two placebo-controlled trials FDA highlighted, with 6 and 16 patients, found no significant benefit[1,2]. In July 2026 an FDA advisory committee voted against adding DSIP to the list of substances pharmacies may compound[3,4].
Mechanism of Action
DSIP's mechanism has never been pinned down, and no dedicated receptor has been identified. FDA's 2026 review summarized the animal evidence this way: naloxone, a drug that blocks opioid receptors, cancels DSIP's sleep-prolonging and pain-relieving effects in animals, which points to involvement of the body's opioid system. Yet DSIP does not appear to bind opioid receptors directly. One proposed explanation is that it nudges nerve cells to release enkephalins, the brain's own opioid-like peptides, through a calcium-dependent process[2].
The peptide is fragile. Animal and lab data put its half-life at under 10 minutes, because enzymes in blood and tissue break it down quickly. It does appear to cross the blood-brain barrier and the barrier into spinal fluid[2]. In human insomnia studies it was given intravenously, and some reported effects began only in the second hour, or showed up on sleep 13 to 22 hours later, a delayed pattern that remains unexplained[1].
What the Research Shows
- Randomized, double-blind, placebo-controlled crossover, 1987 (n=6 with severe chronic insomnia): sleep onset was slightly faster and total sleep rose about 20 minutes, but no difference from placebo or baseline was significant[1,2].
- Double-blind, placebo-controlled trial, 1992 (n=16 with chronic insomnia, three treatment nights): falling asleep was numerically faster, but no objective or subjective sleep measure differed significantly from placebo[1,2].
- Double-blind study with outside comparison group, 1987 (n=14 with insomnia, seven nights): time to fall asleep fell from 58 to 28 minutes and total sleep rose from 313 to 385 minutes. FDA noted there was no placebo arm, which limits interpretation[1].
- Randomized crossover, 1981 (n=6): sleep-promoting effects appeared in the second hour; there were only "tendencies" toward fewer awakenings, and subjective sleepiness did not differ[1].
- Opioid withdrawal, open-label, 1984 and 1998 (n=60 and n=7): 40 of 60 were rated improved in the larger study, with relapse of anxiety and insomnia within days in some. In the smaller one, withdrawal scores fell from 34.4 to 17.8, but only 2 of 7 completed treatment. Neither had a control group[1,2].
- Narcolepsy, single case report, 1984 (n=1): sleep attacks fell from 6 to 3 per period[1].
- Rabbits: DSIP was originally found in rabbit cerebral venous blood, and early work linked it to a type of sleep with increased delta-wave EEG activity[1].
- Rodents and other species (summarized by FDA): sleep-prolonging and analgesic effects that are reversed by naloxone; crossing of the blood-brain barrier; rapid breakdown by peptidases[2].
- FDA found no formal nonclinical toxicity studies and no animal studies of addiction potential, despite the opioid-system link[2].
For people hoping DSIP will deepen sleep, the honest answer is that the best-controlled studies, though tiny, did not show a meaningful benefit over placebo[1,2]. The more positive reports come largely from one research group, often without a placebo comparison, and nearly all used intravenous administration in a lab[1]. FDA reviewers concluded the evidence for insomnia, narcolepsy and opioid withdrawal was insufficient, and found no data at all for injection under the skin[2]. Any sleep benefit remains unproven.
- Insomnia studies: intravenous DSIP was described as well tolerated, but the studies were small and short[2].
- Withdrawal study (n=107): 9 had minor effects such as sweating, headache, nausea or vertigo; 3 had serious events, including low blood pressure after the first injection in 2 people[2].
- No data for common routes: FDA found no safety data for injection under the skin, and flagged immunogenicity risk from aggregates and impurities[1,2].
- No toxicology: no formal nonclinical toxicity or addiction-potential studies were identified[2].
- FDA's adverse event database returned no reports, which FDA cautioned does not mean the substance is safe[2].
Open Questions
- No receptor or clear mechanism has been identified after five decades of research[2].
- No adequately sized, modern placebo-controlled trial has tested DSIP for any sleep disorder[1].
- Claims that DSIP lowers cortisol or boosts nighttime growth hormone in people are not supported by the controlled clinical evidence FDA reviewed[1].
- The safety of repeated use, and of non-intravenous routes, is unstudied[1,2].
Regulatory Status
Not approved by FDA or any major regulator. FDA reviewers recommended against adding emideltide to the 503A bulk substances list, and the Pharmacy Compounding Advisory Committee voted no on July 24, 2026; FDA's final decision was pending at last report[2,3,4]. An earlier nomination had been withdrawn[5]. DSIP is not named on the WADA 2026 list, but unapproved substances fall under the S0 category, banned at all times[6].
Related Compounds
References (6)
- U.S. Food and Drug Administration. FDA Briefing Document for Emideltide-Related Bulk Drug Substances (Emideltide (free base) and Emideltide acetate). Pharmacy Compounding Advisory Committee, July 2026. fda.gov
- U.S. Food and Drug Administration. FDA Presentations, Pharmacy Compounding Advisory Committee, July 24, 2026 (emideltide). fda.gov
- U.S. Food and Drug Administration. July 23-24, 2026 Meeting of the Pharmacy Compounding Advisory Committee. 2026. fda.gov
- American Med Spa Association. FDA Advisory Committee Recommends Adding Six of Seven Peptides to Compounding List. 2026. americanmedspa.org
- U.S. Food and Drug Administration. Certain bulk drug substances for use in compounding that may present significant safety risks (nominated substances withdrawn, including emideltide). Updated April 2026. fda.gov
- World Anti-Doping Agency. 2026 Prohibited List, S0 Non-approved substances. wada-ama.org
Sources last reviewed October 2026.