DSIP

DSIP stands for delta sleep-inducing peptide, and the name is not a description. It is a hypothesis from 1977 that no study has since borne out, attached to the molecule permanently and doing most of the persuasive work ever since.

What makes this entry unusual is that the evidence is not missing. Real double-blind placebo-controlled sleep-laboratory trials with polysomnography were run in insomniacs during the 1980s, which is more human administration evidence than most compounds in this library have. They were run, and the results were weak. Meanwhile the peptide has no identified gene, no isolated protein and no known receptor, and when measured in people its levels rise as deep sleep falls.

DSIP is a chain of nine amino acids, isolated in 1977 from the cerebral venous blood of rabbits that had been induced into a sleep-like state. The group that found it proposed it as a sleep-promoting factor and named it accordingly.

That naming decision has outlived the evidence behind it. A 2006 review in the Journal of Neurochemistry sets out the position with unusual directness: the link between DSIP and sleep was never further characterised, partly because the gene, the protein and any related receptor have never been isolated, and the hypothesis that DSIP is a sleep factor is extremely poorly documented and still weak. Roughly thirty years passed between the isolation and that assessment, and another twenty have passed since without the position changing.

Where the Biology Gets Interesting

There is no established endogenous role, and that is a stronger statement than it first appears. For most compounds in this library the uncertainty is about what happens when you supply the molecule from outside. Here the uncertainty reaches further back: what the molecule does in a body that makes it, or whether the body makes it as a discrete signalling peptide at all, has never been settled.

Material resembling DSIP can be detected in human blood, and its concentration follows a daily rhythm. That rhythm is the closest thing to a physiological role anyone has established, and its direction is the problem described below rather than a supporting finding.

The Mechanism, Without Overstating It

No mechanism has been established, because the components a mechanism would need are missing. There is no identified gene, no protein isolated from tissue, and no receptor. A peptide with a name describing an action, and none of the molecular apparatus that action would require, is an unusual object.

Proposed accounts over the decades have involved modulation of other neurotransmitter systems rather than a direct sleep-promoting receptor, and none has been carried to the point of demonstration. Structure-activity work in animals, which is where a mechanism would normally start to firm up, instead found that the peptide and most of its analogues produced no statistically significant effect on sleep against saline.

The overreach here is structural rather than a matter of degree.

The first problem is that the name is an unconfirmed hypothesis presented as a description. Every time the compound is referred to as delta sleep-inducing peptide, the claim is restated without evidence attached, and nobody has to defend it.

The second is that the molecular basis was never established. No gene, no isolated protein, no receptor, half a century after the original isolation. That is not a gap waiting to be filled by the next study; it is the reason the field moved on.

The third is the direction of the endogenous data. Circulating DSIP-like material is highest when slow wave and REM sleep are lowest, which is the opposite of the relationship the name implies.

The fourth is that the human trials, which are real and were properly designed for their era, reported effects their own authors described as of little clinical significance. That is a conclusion, not an absence of data, and it deserves more weight than a compound that was never studied at all.

The small human trials of the 1980s were conducted under sleep-laboratory conditions with medical supervision and did not report harm, which is worth stating because it is a genuine observation rather than silence. Those studies were small, short, and conducted with pharmaceutical-grade material in a clinical setting.

Beyond that there is nothing. The compound was never developed further, so there is no extended safety assessment, no data on repeated exposure over any meaningful period, and no approved product anywhere against which material sold online could be compared. Material that has been abandoned by research is not the same as material shown to be safe, and the absence of later studies reflects the absence of a demonstrated effect rather than a settled safety record.

On anti-doping, DSIP is not named on the 2026 Prohibited List, which is not permission: S0 prohibits at all times any substance with no current approval by any regulator for human therapeutic use, and DSIP holds none. It sits on neither FDA 503A list today, but not because it was never considered: FDA reviewed it as “Emideltide (DSIP)” and its nomination was withdrawn in April 2026 by the nominator, not resolved by the agency. The safety concerns FDA published at the time still stand. Searching the nominations for delta sleep-inducing peptide returns nothing, because the agency files it under a name the compound is rarely sold as.

Read honestly, this entry supports very little about sleep and quite a lot about how claims survive. A nonapeptide was isolated in 1977 and named for an effect its discoverers proposed. Animal studies through the 1980s did not reproduce that effect. Human sleep-laboratory trials were run and produced results their authors called of little clinical significance. The molecular basis was never established, and the peptide's own daily rhythm in humans runs opposite to what the name implies.

The practical conclusion is that this is not a compound with promising early evidence awaiting confirmation. It is a compound whose evidence was gathered, came back weak, and was then largely abandoned by the field, while the name it was given at the start continued to circulate on its own.

Not demonstrated to induce delta sleep. The name records a hypothesis from 1977 that later animal work did not reproduce and that the human sleep-laboratory trials described as producing improvement of little clinical significance.

Not an established endogenous signalling peptide. No gene, no protein isolated from tissue and no receptor have been identified, which a 2006 review in the Journal of Neurochemistry describes as leaving the sleep-factor hypothesis extremely poorly documented.

Not consistent with its own endogenous rhythm. Circulating DSIP-like material in humans correlates negatively with slow wave and REM sleep, so the peptide is highest when deep sleep is least.

Not an untested compound. Double-blind polysomnographic trials were run in insomniacs in the 1980s, which makes this a question that was asked and answered rather than one still open.

Not a protocol or personal-use guide. The human work here is small, mostly decades old, and inconsistent between studies, so this page reports what was measured rather than what it would do for you.

DSIP is the clearest case in this library of a name outliving its evidence. Almost every other compound here has an evidence problem of the ordinary kind: too little data, or data from the wrong species, or data about a neighbouring molecule. This one was studied properly for its era, in people, with the right instruments, and the answer was largely no.

What kept it alive was four words attached to it in 1977. That is worth sitting with, because it is the cheapest and most durable form of evidence a compound can have, and it costs nothing to manufacture. We cover DSIP because recognising a name doing the work of a study is a skill that transfers to everything else on this site.