# Sermorelin: GHRH(1-29), the Nocturnal GH Pulse, and What the Studies Measured > Sermorelin is the GHRH(1-29) peptide that stimulates the body's own pulsatile growth-hormone release. A cited, plain-English digest of the mechanism, the dose record, and the open questions. A pinned, cited digest of how sermorelin works, what the studies actually measured, and where the adult evidence runs out — with the body-composition data marked as the related analog where it belongs. ## The short version Sermorelin is a lab-made copy of the first 29 amino acids of GHRH (growth hormone-releasing hormone — the brain's own "make growth hormone" signal). Instead of injecting growth hormone directly, it nudges the pituitary gland to release the body's own, in the natural bursts it normally fires — most strongly during deep sleep. In growth-deficient children it sped up growth, and in older men it pushed an aged growth-hormone system back toward a younger range. It was a prescription drug decades ago, was pulled from the US market in 2008 for business reasons, and is now made by compounding pharmacies. The adult "anti-aging" claims run ahead of the evidence — this digest keeps the findings and the gaps side by side. ## What is sermorelin? Sermorelin is a synthetic 29-amino-acid peptide that copies the amino-terminal 1-29 fragment of human GHRH — the shortest piece of GHRH that still fully activates the GHRH receptor [1]. Chemically it carries an amidated tail, weighs about 3,357.9 Da, and is the active part of a 44-amino-acid hormone the hypothalamus normally releases to tell the pituitary to make growth hormone. Functionally, it is a growth-hormone secretagogue — something that prompts a gland to release its hormone rather than supplying that hormone from outside. Because it acts one step upstream, on the pituitary, the body's own brakes (somatostatin, the inhibitory hormone, and IGF-1 feedback) stay in place, so growth hormone is still released in its natural pulsatile pattern — in bursts, not a steady drip. In its approved era, sermorelin treated and helped evaluate growth-hormone deficiency in children, where once-daily subcutaneous dosing accelerated growth without driving IGF-1 (a growth signal the liver makes when GH rises) past the normal range [2]. The adult research record — aging, sleep, cognition, body composition — is the larger body of work this site reads, always as study findings rather than guidance. ### What does sermorelin do to the body? It binds GHRH receptors on the growth-hormone-producing cells of the pituitary and switches on the cAMP/PKA signaling cascade, stimulating the body's own pulsatile growth-hormone release, which in turn raises liver-made IGF-1 [1]. Because it works through the body's own feedback loop, somatostatin and IGF-1 keep regulating the system. In older men, this upstream nudge was enough to reverse age-related declines: subcutaneous GHRH(1-29) twice daily for 14 days raised 24-hour GH and IGF-1 in a dose-related way [3]. ## Sermorelin: the GHRH(1-29) peptide Calling it the **sermorelin peptide** is precise: it is a single, defined 29-residue chain, not a blend. It belongs to the GHRH-analog class — the family of peptides built on the natural GHRH signal — and is distinct from the GHRPs (growth-hormone-releasing peptides) such as ipamorelin, which act on a completely different receptor (the ghrelin/GHS receptor) [4]. The identity matters because the literature pairs sermorelin with two neighbors. CJC-1295 and tesamorelin are longer-acting GHRH analogs engineered to outlast sermorelin's brief life in the blood, while the GHRPs reach the same end point — more growth hormone — by a separate door. Throughout this digest, GHRH-analog findings (sermorelin's own family) are kept apart from GHRP findings, and a related-analog result is never relabeled as a direct sermorelin result. ### Sermorelin acetate Research and compounded material is supplied as **sermorelin acetate** — the acetate salt of GHRH(1-29), a lyophilized (freeze-dried) powder reconstituted before use. The salt form is what stabilizes a peptide that degrades readily in solution; the underlying molecule and its receptor activity are identical to the free peptide [5]. Machine identifiers — CAS 86168-78-7, PubChem CID 16132413, formula C149H246N44O42S — sit in the [full reference list](/references) for anyone matching lots to literature. ## Sermorelin mechanism of action The **sermorelin mechanism of action** is receptor-level and well characterized. Sermorelin binds the GHRH receptor (GHRH-R), a class B G-protein-coupled receptor sitting on pituitary somatotrophs — the cells whose only job is to make growth hormone. Binding activates the Gs/adenylate cyclase pathway, raising cyclic AMP (cAMP), which switches on protein kinase A (PKA) [1]. That signal does two things: it increases transcription of the growth-hormone gene, and it triggers release of stored growth hormone in a pulse. Repeated GHRH signaling is also trophic — it supports the somatotroph population itself. Downstream, the released growth hormone reaches the liver and drives IGF-1 production, the hormone that carries out many of GH's effects and then feeds back to dampen further GH release. The design consequence is the headline feature of the class: because sermorelin acts above the pituitary rather than replacing growth hormone, the pulsatile rhythm and the somatostatin/IGF-1 feedback loop are preserved. An editorial argued this makes a secretagogue a more physiologic route to adult growth-hormone insufficiency than supplying recombinant hormone directly [6]. That is an argument in the literature — not a treatment recommendation. ### How does sermorelin work to stimulate growth hormone production? It binds the GHRH receptor on pituitary somatotrophs and activates Gs/adenylate-cyclase/cAMP/PKA signaling, increasing GH gene transcription and triggering a pulse of GH release; the released GH then drives hepatic IGF-1, while somatostatin and IGF-1 feedback — left intact by this upstream action — preserve the natural pulsatile pattern [1]. ## What the night file holds This is a layered reading board, not a storefront. The clippings are organized so each line of evidence can be read against its source and its limit: - **[Sermorelin and sleep](/sleep-and-gh)** — the slow-wave-sleep and nocturnal-GH-pulse evidence, the night-injection and timing questions, and why GHRH's sleep effects depend on the clock. - **[The GHRH research findings](/research)** — mechanism, the pediatric and aging data, the GHRH-analog cognition trial, and honest comparisons with tesamorelin and ipamorelin. - **[Sermorelin vs CJC-1295](/vs-cjc-1295)** — two GHRH-receptor agonists, one short-lived and one half-life-extended, and what that engineering changes. - **[Doses studied in the literature](/dosage)** — the research-context dose record, route, and half-life, in study framing only. The honest gaps stay pinned in plain view: adult anti-aging marketing outpaces the direct sermorelin evidence, the strongest body-composition numbers belong to the related analog tesamorelin, and there is no defined adult "course length" in this record [7]. --- A night research board of the sermorelin literature — slow-wave sleep, the nocturnal growth-hormone pulse, and the GHRH(1-29) findings pinned and cited, with the body-composition data taped where it belongs as tesamorelin and the empty adult-safety clipping left torn open; no clinic behind the board and nothing here dosed, dispensed, or sold.