# DSIP: The Delta Sleep-Inducing Peptide and Its Unsolved Riddle > DSIP, the delta sleep-inducing peptide, was drawn from the blood of sleeping rabbits in 1977. A nocturnal digest of the slow-wave findings, the missing receptor, and the studies that found nothing. A digest of the delta sleep-inducing peptide — the slow-wave findings, the experiments that found nothing, and the receptor that has never been seen — every claim pinned to its source. ## Before the details DSIP stands for delta sleep-inducing peptide. It is a tiny natural molecule — nine amino acids strung in a row — first pulled from the blood of rabbits while they slept. Scientists named it for the slow, deep brain waves (called delta waves) it seemed to stir up when they dripped it into the brain. Here is the honest part. After more than forty years, no one has found the receptor — the lock this key is supposed to fit. People who try it for sleep get mixed results: some say they sleep deeper and wake clearer, and a large share say they feel nothing at all. The small human studies were old and modest, and DSIP is not approved as a medicine anywhere. This site reads the studies plainly, says where the evidence is thin, and keeps the downsides in full view — what people report, including the misses, is on [the effects page](/effects). No dosing advice lives here. ## The peptide that named a brain-wave DSIP entered science in 1977, when two researchers isolated a nine-amino-acid peptide — sequence Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu — from the cerebral blood of rabbits whose brains had been coaxed into sleep, and showed that infusing it deepened the slow delta waves of slumber [1]. The molecule took its name from those waves: the delta sleep-inducing peptide, a messenger fished out of sleep itself. It is small and it is everywhere and it is barely understood. DSIP turns up in plasma, in cerebrospinal fluid, even in milk, usually riding a carrier protein. Yet for all that presence, no DSIP gene, no precursor protein, and no specific receptor has ever been conclusively found [3]. Forty years of searching, and the lock is still missing. That absence is not a footnote — it is the whole character of the compound. A 2006 review in a neurochemistry journal called DSIP a 'still unresolved riddle' and judged the evidence that it actually promotes sleep to be 'extremely poorly documented and still weak' [3]. This site does not paper over that line. It reads it aloud. ## DSIP for sleep — what the studies actually measured The clearest human signal is old and slight. In a 1981 study, intravenous synthetic DSIP given to six middle-aged chronic insomniacs lengthened their sleep, cut the interruptions, nudged REM upward, and left no daytime grogginess behind — the effect surfacing in the second hour after the injection rather than at once [2]. A later double-blind study in chronic insomniacs found higher sleep efficiency and shorter time-to-sleep against placebo, but the authors themselves called the effect modest and concluded that short-term treatment alone was unlikely to be of major benefit [18]. That is the shape of the sleep evidence: real enough to keep researchers curious, thin enough that no one should oversell it. The strongest sleep effects in the later literature came not from native DSIP but from engineered structural analogs — a telling detail [3]. For the deeper reading, see the [DSIP research](/research). ## A molecule of many doors, none of them open Strip away the sleep story and DSIP still refuses to sit still. In rats it raised growth hormone through a brain pathway that the drug pimozide could block [9] — yet in women, the same peptide moved neither growth hormone nor prolactin [10]. An early human study saw it lower the stress hormone ACTH while leaving cortisol untouched [4]; a later human study saw it touch neither [8]. The pattern repeats: a striking finding in animals, a quiet null in people. Even its dose-response is strange. DSIP follows a parabolic curve — effect rising, then falling, as the dose climbs — so more is not reliably stronger [7]. It is a compound that seems to do many things and reliably does almost none. The honest reader holds both halves at once. ## What this site is rxDSIP is an independent editorial digest of the peer-reviewed literature on the delta sleep-inducing peptide. It is not a clinic and it sells nothing. It exists to gather the scattered DSIP studies — the rabbit blood, the insomnia pilots, the contradictory hormone work, the long-life mouse data — into one calm, cited, plain-spoken place, and to be as clear about the gaps as about the findings. The 'rx' in the name marks a position relative to the literature, not a pharmacy. Begin with the [delta sleep inducing peptide](/what-is-dsip) primer, weigh the [DSIP effects](/effects), or read the [DSIP references](/references) in full. --- A nocturnal field guide to DSIP, the delta sleep-inducing peptide — the slow-wave findings drawn out where the studies show them, the missing receptor and the nights nothing happened left openly in the dark, with no clinic at the bedside and nothing here dosed, supplied, or sold.