DSIP vs melatonin: melatonin has far stronger evidence. A meta-analysis of 19 trials found it helps people fall asleep about 7 minutes faster and sleep about 8 minutes longer than placebo, a small but consistent effect.[7] DSIP (delta sleep-inducing peptide) was tested in only a handful of tiny IV studies in the 1980s with mixed results, and FDA called that evidence “inconclusive and at best preliminary.”[1] Melatonin is a widely available supplement; DSIP is unapproved everywhere FDA looked.
Both are sold for sleep, but they are very different products. See our DSIP profile for its full history, and the nootropic peptides hub for related compounds.
At a glance
| DSIP | Melatonin | |
|---|---|---|
| What it is | 9-amino-acid peptide found in rabbits in 1977[2] | Hormone made by the body’s pineal gland[10] |
| How it’s sold | Unapproved injections and nasal sprays[1] | Dietary supplement in the US; prescription in some countries[10] |
| Human evidence | A few IV studies, 6 to 18 people each[1] | Dozens of randomized trials[7] |
| Effect on sleep | Inconsistent; two double-blind trials found little benefit[5][6] | Modest: about 7 minutes faster to sleep[7] |
| Half-life | About 8 minutes in human plasma[1] | Short; varies by product |
| Guideline support | None | Recommended for some body-clock disorders[9] |
| US legal status | Not approved; advisers voted against compounding[14] | Legal over-the-counter supplement[10] |
How each works
Melatonin is the body’s own darkness signal. It rises in the evening and helps time the body clock, which is why it works best for problems of timing, such as jet lag or a body clock that runs late.[10][9]
DSIP got its name when Swiss researchers infused it into rabbits’ brains and saw more slow-wave “delta” brain activity.[2] Its actual role is still unclear. Sleep researchers wrote in 2006 that no DSIP gene, parent protein or receptor had been found, so its link to sleep has never been properly explained.[3] In animal studies it seems to work through opioid-related pathways without binding opioid receptors directly, and in people its blood half-life is only about 8 minutes, so any effect would have to be indirect.[1]
Evidence quality: what the trials found
DSIP
| Study | Design | Result |
|---|---|---|
| Schneider-Helmert, 1986 (18 adults) | IV DSIP, compared with outside healthy controls, no placebo group | Sleep improved toward normal[4] |
| Monti et al., 1987 | Double-blind crossover | No significant difference from placebo[5] |
| Bes et al., 1992 (16 adults) | Double-blind, placebo group | Weak effects, possibly due to chance[6] |
Across every published study, FDA counted just 209 people who ever received IV DSIP. No study has tested it injected under the skin or sprayed in the nose, the way it is sold now.[1]
Melatonin
- Meta-analysis: 19 trials in 1,683 people showed shorter time to fall asleep (about 7 minutes), slightly more total sleep (about 8 minutes) and better sleep quality than placebo.[7]
- Chronic insomnia: the American Academy of Sleep Medicine suggests clinicians not use melatonin for chronic insomnia in adults, a weak recommendation, because the benefit is small.[8]
- Body-clock disorders: the same academy supports timed melatonin for delayed sleep-wake phase disorder, for blind adults with non-24-hour rhythms, and for some children with neurological conditions.[9]
Side effects and safety
DSIP
- No significant side effects were reported in the small IV insomnia studies.[1]
- In a withdrawal study, a few patients had headache, sweating, nausea or dizziness, and some had a drop in blood pressure.[1]
- FDA found no animal toxicity studies and no data on addiction potential, which it flagged because DSIP acts on opioid-related pathways in animals.[1]
- FDA also warns that injected peptides can trigger immune reactions and that commercial products may contain impurities.[15]
Melatonin
- Short-term use appears safe for most people; mild headache, dizziness, nausea and sleepiness are the usual side effects. Long-term safety is not well studied.[10]
- Dose accuracy is a real problem. In a 2017 study, melatonin content ranged from 83% below to 478% above the label, and 26% of products contained serotonin.[11] A 2023 study of gummies found most were mislabeled, some with about 3.5 times the stated amount.[12][10]
- Children: reported pediatric melatonin ingestions rose 530% from 2012 to 2021, with some hospitalizations.[13] Keep it out of reach and ask a pediatrician before giving it.
- Older adults may feel drowsy the next day, and people on blood thinners or with epilepsy should check with a clinician first.[10]
Legal status and access
- DSIP: not approved in the US or registered as a drug in any country FDA searched.[1] At its July 24, 2026 meeting, FDA’s compounding advisory committee reportedly voted 6 to 7, with one abstention, against adding it to the list pharmacies may use. FDA has not issued a final decision.[14] It is not on WADA’s 2026 list by name, but as an unapproved substance it likely falls under the non-approved substances category.[16]
- Melatonin: sold as a dietary supplement in the US, so FDA does not review it for effectiveness before sale; several other countries require a prescription.[10]
For other peptides reviewed at the same meeting, see the FDA peptide ban in 2026.
Who each may suit: questions for your clinician
- “I can’t fall asleep at a normal time.” Ask whether a delayed body clock could be the cause and whether timed, low-dose melatonin makes sense.[9]
- “I’m flying across time zones.” Ask about melatonin for jet lag.[10]
- “I wake up often or feel unrested.” Ask about sleep apnea testing and CBT-I before any supplement.
- “I’ve read DSIP gives deeper sleep.” Ask what evidence supports it in people. There is little, and no tested dose for the forms sold today.[1]
The verdict
Melatonin wins on evidence, cost, access and legality, but its benefit is small and supplement quality varies. DSIP’s reputation rests on a 1977 rabbit study and a few small 1980s trials that did not hold up well under blinding. What isn’t known: whether DSIP works at all in people, and whether it is safe when injected under the skin.
For other “brain” peptides, see Dihexa vs Semax vs Selank and Selank vs Semax.
