DSIP (Delta Sleep-Inducing Peptide): Discovery, Human Studies and Open Questions

DSIP was one of the first candidate "sleep factors" purified from blood. It was tested in animals and people for roughly two decades, then interest faded without a clear answer. The name is historical: it describes what the discoverers saw in rabbits, not an established property of the molecule.

Where did DSIP come from?

The work began in Monnier's laboratory in Basel. In 1964 Monnier and Hösli filtered (dialysed) blood leaving the brain of rabbits whose sleep had been induced by electrical stimulation of the thalamus. Giving that dialysate to other rabbits produced moderate sleep, while dialysate from donors kept awake by stimulation caused arousal (Monnier and Hösli, 1964).

Over the next decade the group purified the active fraction, which they called "factor delta". In 1977 Schoenenberger and Monnier reported its sequence, Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu, made it synthetically and named it delta sleep-inducing peptide. Infused into the brain ventricles of rabbits under double-blind conditions, it was the only one of nine synthetic peptides tested, in 58 rabbits including controls, to enhance delta and spindle patterns on the EEG (Schoenenberger and Monnier, 1977). Delta waves are the slow, large brain waves of deep non-REM sleep. Its structure does not resemble any other known peptide family (Kovalzon and Strekalova, 2006).

What did the animal studies show?

Early reports were encouraging. A 1984 review summarised DSIP as increasing mainly delta sleep in rabbits, rats and mice, while in cats the effect fell more on REM sleep (Graf and Kastin, 1984). In a 1988 rat study, an antiserum against DSIP placed in the brain blocked the rebound in deep sleep and growth hormone that normally follows sleep deprivation, which the authors read as a sign of a natural role (Iyer et al., 1988).

Other laboratories did not see the same thing. In Zürich, DSIP given to rats systemically did not significantly reduce their activity, and given into the brain ventricles it did not significantly increase sleep or EEG delta power in the following two hours; the authors concluded it did not qualify as a specific sleep-promoting substance (Tobler and Borbély, 1980). A Moscow group found that some stabilised synthetic analogues promoted slow-wave sleep in rabbits and rats, but DSIP itself did not (Kovalzon and Strekalova, 2006). A 2003 review listed DSIP among four sleep factors found in blood-transfer experiments for which a physiological role in regulating sleep has not been determined (Obal and Krueger, 2003).

What did the human studies find?

The first human study, in six healthy volunteers under double-blind crossover conditions, reported a feeling of sleep pressure and more sleep in the two hours after DSIP than after placebo (Schneider-Helmert et al., 1981). Studies in chronic insomnia followed:

• Six middle-aged insomniacs: longer sleep with fewer interruptions, after a slight arousing effect in the first hour (Schneider-Helmert and Schoenenberger, 1981).
• 18 insomniacs in two age groups: sleep moved to normal values over one to two weeks (Schneider-Helmert, 1986), judged against healthy reference values rather than a placebo group.
• 14 insomniacs: better night sleep and daytime performance than at their own baseline (Schneider-Helmert, 1987). FDA's 2026 review noted that, despite the description, the study had no placebo arm.
• Six severe insomniacs, placebo-controlled crossover: differences from placebo were of little clinical significance (Monti et al., 1987).
• 16 insomniacs, placebo-controlled, Amsterdam: weak effects that may partly reflect a chance change in the placebo group; the authors judged DSIP unlikely to be of major benefit (Bes et al., 1992).

The most positive results came from Schneider-Helmert, who co-authored the first human papers with the discoverers, and his later studies lacked a placebo group. The placebo-controlled studies from other centres found little.

DSIP was also tested in hospital patients withdrawing from alcohol or opiates. In Geneva, 107 inpatients were judged by doctors and nurses, with no comparison group; symptoms reportedly resolved or improved markedly in 97% of evaluated opiate patients and 87% of alcohol patients, but 13% and 22% of the two groups could not be evaluated (Dick et al., 1984). A 1998 open study in seven people withdrawing from opioids ended with only two completing the planned course, and its authors called for placebo-controlled trials (Backmund et al., 1998; FDA, 2026).

One later study ran against the peptide's name. In a randomised study of 24 women having general anaesthesia in Manchester, 12 of whom received DSIP, the authors found that it paradoxically reduced delta activity and lightened anaesthesia as measured by an EEG-based monitor (Pomfrett et al., 2009). Reviewing the sleep evidence in 2026, FDA described the insomnia studies as "inconclusive and at best preliminary" (FDA briefing document, 2026).

Why is DSIP still unexplained?

• No gene, precursor or receptor. Nearly 30 years after its discovery, no DSIP gene, protein precursor or receptor had been isolated (Kovalzon and Strekalova, 2006). A 2011 database search found a close match, differing at two positions, inside a family of histone-modifying enzymes and proposed them as possible precursors of DSIP-like peptides; that remains a suggestion (Mikhaleva et al., 2011).
• The antibody problem. Much of the evidence that DSIP occurs naturally came from antibody tests. In 1993 a 77-amino-acid protein from pig brain, unrelated to DSIP in sequence, was shown to react with a DSIP antiserum (Sillard et al., 1993); it is now known as glucocorticoid-induced leucine zipper, or GILZ (Gimble et al., 2009). Kovalzon and Strekalova proposed that other DSIP-like peptides explain at least part of what was measured.
• Getting into the brain. Kastin and Banks found that small amounts of intact DSIP cross from blood into the rat brain and dog cerebrospinal fluid (Kastin et al., 1981; Banks et al., 1982), but whether peptides in the blood reach the brain at all was then described as controversial (Miller et al., 1986), and cells from a blood-brain barrier model break DSIP down (Augustijns et al., 1995).
• Instability in blood. DSIP disappears from blood quickly because enzymes break it down (Graf et al., 1987). FDA's review gives half-lives of minutes, around 5 to 10 in human serum in the laboratory (FDA, 2026). Whether this explains DSIP's variable effects was left open.

What else has DSIP been studied for?

Stress response. Much of the later DSIP literature comes from Russian institutes (see our overview of Russian cognitive peptides). In one Moscow rat study, DSIP reduced stress-induced activation of the hypothalamus and septum, mainly in stress-susceptible rats (Sudakov et al., 2001).

Hormones. In rats, DSIP raised luteinising hormone (LH) through an apparent action on the hypothalamus rather than the pituitary (Iyer and McCann, 1987) and reduced the corticosterone response to the stress hormone CRF (Graf et al., 1985). Human results conflict: in 11 healthy men, ACTH-like material in blood fell while cortisol was unchanged (Bjartell et al., 1989), but a German study found no effect on stimulated ACTH or cortisol (Späth-Schwalbe et al., 1995).

Ageing in mice. In female SHR mice, the strain also used in the Epitalon lifespan work covered in our bioregulator guide, a Russian preparation of DSIP mixed with glycine, Deltaran, was linked to longer survival in the oldest 10% and slower development of spontaneous tumours (Voitenkov et al., 2009). FDA noted that glycine itself has reported anti-tumour properties, so the result cannot be credited to DSIP alone (FDA, 2026).

Is DSIP an approved medicine?

No. FDA's 2026 briefing states that DSIP is not a component of any FDA-approved drug, is not in the European, Japanese or International pharmacopoeias, and is not a registered drug in any country FDA searched. FDA proposed not adding it to the list of substances US pharmacies may use in compounding (FDA, 2026). Its advisory committee considered it on 24 July 2026 (FDA meeting page), and the vote failed 6 to 7 with one abstention (FDA Law Blog, 2026). The vote is advisory, and we found no final FDA decision as of October 2026.

What is not known?

• Whether DSIP is made in the body as a free peptide, and from which gene.
• What it binds to, and whether its reported effects share one mechanism.
• How much intact DSIP reaches the brain, given that it breaks down within minutes.
• Whether any effect on human sleep is real: there has been no large, independent, placebo-controlled trial.
• Whether reported effects come from DSIP itself, its fragments, or other DSIP-like molecules.
• Longer-term safety: FDA found no nonclinical toxicity studies (FDA, 2026).

The bottom line

DSIP is a well-defined nonapeptide with a poorly defined biology. The animal findings disagreed, the human studies were small, old and conflicting, and where it comes from and what it acts on were never established. It is best read as a research peptide with a historic name. More detail is on the DSIP compound page.

References

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