Page data last changed: . Chemistry registry snapshot: . Registry refreshes and identity assessments are separate from scientific content review.
Hypothalamic peptide central to the sleep–wake system.
Also known as: Hypocretin-1
Part of the Neuropeptides & signaling cluster
Overview
Orexin-A (hypocretin-1) is a 33-amino-acid hypothalamic neuropeptide central to the regulation of wakefulness and arousal. Loss of orexin signaling is a well-studied feature of narcolepsy research.
Source & context
Biological / chemical source: Lateral hypothalamus
Primary research or clinical context: Sleep and neuroscience research
Sleep–wake biology
Orexin-A and orexin-B are produced by a small population of lateral-hypothalamic neurons and act through OX1 and OX2 receptors to stabilize wakefulness. Their study reshaped understanding of narcolepsy and the neuroscience of arousal.
Structure note
Orexin-A contains two intrachain disulfide bonds and an amidated C-terminus that contribute to its stability. This page describes its physiology for education only.
Structure & chemistry
Molecular identity & reference confidence
Source-supported reference
Reference values are taken from the cited molecular record or curated profile. A database match is not independent laboratory verification; modifications, counter-ions, and formulations can change the measured mass.
- Molecular form
- Orexin-A (source record; form not independently established)
- Species
- Not established by this molecular identity audit
- Termini (N / C)
- Not specified / Not specified
Average reference mass
Reference policy updated: 2026-10-05
- IUPHAR/BPS source snapshot · 2026-10-01
- PubChem molecular record · 2026-10-01
- Molecular formula
- C152H243N47O44S4
- Average reference mass
- ≈ 3,561.1
- PubChem CID: 56842143
- IUPHAR ligand: 1697
- CAS RN: 205640-90-0
- UNII: 8RDY08V4VC
Chemistry values: PubChem, IUPHAR/BPS Guide to Pharmacology · fetched 2026-10-01.
Clinical development snapshot
ClinicalTrials.gov lists 77 registered studies with “Orexin-A” as an intervention (snapshot 2026-10-01). A registry footprint is not evidence of efficacy or approval.
| NCT | Title | Phase | Status | Updated |
|---|---|---|---|---|
| NCT07847021 | A Multicenter Observational Study of Daridorexant in the Treatment of Insomnia | — | not yet recruiting | 2026-09-29 |
| NCT03999099 | Targeting Orexin to Treat Nicotine Dependence | Phase 1 | completed | 2026-09-21 |
| NCT07830303 | Daridorexant for Sleep Disturbance in Adults With Liver Cirrhosis | Phase 4 | not yet recruiting | 2026-09-21 |
| NCT07214207 | Orexin Receptor Antagonism for the Treatment of Alcohol Use Disorder and Stress-Related Drinking | Phase 2 | recruiting | 2026-09-21 |
| NCT06823752 | A Dual Orexin Receptor Antagonist to Reduce Biomarkers of Neurodegeneration in Adults With Insomnia. | Phase 2 | recruiting | 2026-09-18 |
| NCT05630781 | Orexin s Role in the Neurobiology of Substance Use Disorder | Not applicable | recruiting | 2026-09-11 |
Orexin-A — reconstitution calculator
Enter how much peptide is in the vial and how much diluent (e.g. bacteriostatic water) is added. The tool returns the resulting solution concentration — and, for any amount you type, the volume it corresponds to. This is educational arithmetic, not a dosing recommendation.
Reference form: Orexin-A (source record; form not independently established)Average reference mass: 3,561.1 Da
Enter an amount to see the volume it corresponds to.
Educational concentration mathematics only. This tool does not recommend a dose, amount, or protocol, and nothing here is medical advice. Many peptides are not authorized by Health Canada for human use — see our reconstitution and bacteriostatic-water guides for context.
Change log
Dated observations from the data pipeline (registry flags, trial footprints, identifiers) and editorial reviews of this profile.
- Trials2 registered studies added on ClinicalTrials.gov (now 77).
FAQ about Orexin-A
What is Orexin-A?+
Orexin-A (hypocretin-1) is a 33-amino-acid hypothalamic neuropeptide central to the regulation of wakefulness and arousal. Loss of orexin signaling is a well-studied feature of narcolepsy research.
What Canadian product status is recorded for Orexin-A?+
Canadian product status for Orexin-A has not been verified in this profile. No verified record here does not mean no authorization exists. Status depends on the product, formulation and use; consult Health Canada's product records.
What is the typical length of Orexin-A?+
Orexin-A is commonly described as approximately 33 amino acids (Neuropeptide).
Related peptides
References & further reading
- 1.Vialaret et al. (2025). 16-mer hypocretin-1/orexin-A in cerebrospinal fluid to diagnose narcolepsy. Sleep
- 2.Amodeo et al. (2020). Adolescent alcohol exposure increases orexin-A/hypocretin-1 in the anterior hypothalamus. Alcohol
- 3.Slonkova et al. (2024). Hypocretin-1/orexin-A, sleep and excessive daytime sleepiness in patients with nonconvulsive status epilepticus: A cross-sectional cohort study. Sleep Med
- 4.Wenz et al. (2026). Hypocretin-1/ Orexin-A fragment1-16 as a potential surrogate marker for diagnosing narcolepsy type 1. Sleep
- 5.Tunisi et al. (2021). Orexin-A/Hypocretin-1 Controls the VTA-NAc Mesolimbic Pathway via Endocannabinoid-Mediated Disinhibition of Dopaminergic Neurons in Obese Mice. Front Synaptic Neurosci
- 6.Borgland et al. (2009). Orexin A/hypocretin-1 selectively promotes motivation for positive reinforcers. J Neurosci
- 7.Samzadeh et al. (2020). Decreased Cerebrospinal Fluid Orexin-A (Hypocretin-1) Concentrations in Patients after Generalized Convulsive Status Epilepticus. J Clin Med
- 8.Kukkonen et al. (2025). Detection of reduced orexin-A/hypocretin-1 and its fragments by orexin-A "gold-standard" radioimmunoassay. Sleep Med
- 9.PubChem — compound summary for Orexin-A (CID 56842143)
- 10.Wikipedia — Orexin