Where the name came from
Delta sleep-inducing peptide was isolated in the 1970s from the blood of rabbits in an induced sleep state. The researchers named it for what they were looking at, and the name has done the marketing ever since.
That is the thing worth knowing. The compound is named after an observed correlation in an animal model, not after a demonstrated effect in people. Human work since has been inconsistent: some studies report improved sleep onset or quality, others find nothing distinguishable from placebo.
Sleep is also the single hardest endpoint to study honestly, because expectation affects reported sleep quality more than almost any other self-assessed outcome.
What it is
BioLongevity Labs
DSIP (5mg)
A nine-amino-acid peptide. Beyond sleep, the research literature has looked at it in connection with stress response, pain modulation and withdrawal symptoms, with similarly thin results.
Both vendors we review stock it. BioLongevity Labs sells a 5mg lyophilised vial. Limitless Biotech sells a nasal spray.
The dosing figures
From community protocols and vendor literature, not from dose-finding trials. Same caveat as everything else in this category, and we state it every time rather than once.
The common figure is 100 to 300mcg, taken before bed, which matches the use case. Some protocols describe short runs of five to ten days rather than continuous use.
At 100mcg a night, a 5mg vial is fifty doses. At 300mcg it is sixteen. That makes DSIP one of the cheaper compounds per night of use in the catalogue.
| Dose | Volume | Units | Nights per vial |
|---|---|---|---|
| 100 mcg | 0.04 ml | 4 units | 50 |
| 150 mcg | 0.06 ml | 6 units | 33 |
| 200 mcg | 0.08 ml | 8 units | 25 |
| 300 mcg | 0.12 ml | 12 units | 16 |
5mg vial in 2ml water, U-100 syringe
A note on those small volumes
Four units is a very short draw and sits right at the limit of what you can measure accurately on a syringe barrel. This is exactly the situation where adding more bacteriostatic water helps: it does not change the dose, it spreads the same dose over more of the barrel.
Reconstituting the same 5mg vial with 5ml instead of 2ml puts 100mcg at 10 units rather than 4, which is far easier to read. Our calculator lets you try both before you commit, and our reconstitution guide explains why the water volume is a measurement decision rather than a dosing one.
The nasal spray question
Limitless sells DSIP as a nasal spray, and `dsip peptide nasal spray` is a real search term, so it deserves a straight answer rather than a shrug.
Nine amino acids is large for nasal absorption. The nasal route works well for small molecules and for some specifically engineered peptides. For a nine-residue peptide with no absorption enhancer disclosed, the fraction that actually reaches circulation is an open question.
What we could not find is published bioavailability data for DSIP delivered nasally. Not from the vendor, not in the literature. So the comparison between a spray and an injected vial cannot be made on numbers.
If convenience matters more than certainty about dose delivered, the spray is the easier format. If you want to know how much actually arrived, the vial is the one where the arithmetic is at least knowable.
Where we land
DSIP is cheap per night, has a long history, and carries a name that overstates what has been shown in humans. The sleep evidence is genuinely mixed rather than absent, which puts it ahead of several compounds in this catalogue and well behind anything you would call established.
If sleep is the actual problem, the boring interventions have far better evidence behind them, and a clinician is a better starting point than a vial. Our are peptides safe page covers the risk picture, everything here is sold for research use, and nothing on this page is medical advice.