Not medical advice. Talk to your provider before using any peptide.
Full disclaimer
Orexin (Hypocretin)33 residuesQPLPDCCRQKTCSCRLYELLHGAGNHAAGILTMEach bubble = one amino acid. Size = residue mass. Color = chemical class.Also known as: Hypocretin-1, OX-A, Hcrt-1
Only 22 published human subjects. That's the entire evidence base for intranasal Orexin-A, a 33-amino-acid neuropeptide that controls whether you stay awake or fall asleep. The orexin system is so validated that two FDA-approved drugs (suvorexant, lemborexant) block it to treat insomnia. But using the native peptide itself? That's still deep research territory. Narcolepsy type 1 researchers and sleep neuroscience investigators are the primary audience here, drawn by a compelling biological target that the pharmaceutical industry chose to pursue with small molecules instead.
Two labs discovered it in the same year. In 1998, Sakurai's group called it orexin; de Lecea's group named it hypocretin. Both were right about its importance. Orexin-A (Hypocretin-1) is a 33-amino-acid neuropeptide produced by roughly 70,000 neurons in the lateral hypothalamus. Those neurons project to every major arousal center in the brain. When those neurons die, narcolepsy type 1 results. Cerebrospinal fluid Orexin-A below 110 pg/mL confirms the diagnosis. The FDA validated the orexin system as a drug target by approving suvorexant and lemborexant, both dual orexin receptor antagonists for insomnia. The native peptide is a different story. Only two published human studies exist using exogenous intranasal Orexin-A: Barateau's 2013 narcolepsy trial (n=12)[1] showed fewer wake-REM transitions at 435 nmol, and Trinder's 2022 pilot (n=10)[2] confirmed significant sympathetic nerve activation at 500 nmol in healthy men. Both used ~1,550-1,780 mcg intranasally. Community protocols at 10-50 mcg sit 30-178x below those doses and have no documented CNS efficacy. The research field has moved on to small-molecule OX2R agonists like oveporexton, which received FDA Priority Review in February 2026. The native peptide stays a research tool, not a therapeutic candidate.
Orexin-A and Orexin-B bind two G-protein-coupled receptors, OX1R and OX2R. OX1R couples to Gq proteins, activating phospholipase C and triggering intracellular calcium release through inositol trisphosphate signaling. OX2R couples to both Gq and Gi/Go pathways, giving it a broader modulatory profile. OX1R has a tenfold preference for Orexin-A over Orexin-B; OX2R binds both peptides with similar affinity. OX2R drives most of the wakefulness effect. The flip-flop model of sleep-wake switching depends on orexin neurons as the stabilizer. These neurons collect inputs from the circadian clock (suprachiasmatic nucleus), sleep pressure signals (adenosine buildup), and metabolic sensors (leptin, ghrelin, glucose). They then fire excitatory projections across all major arousal systems: locus coeruleus for norepinephrine, tuberomammillary nucleus for histamine, dorsal raphe for serotonin, ventral tegmental area for dopamine, and basal forebrain for acetylcholine. The appetite connection runs through OX1R projections to the arcuate nucleus. Reward-related effects come from OX1R-dense projections to the ventral tegmental area, where orexin boosts dopaminergic signaling. Cardiovascular sympathoexcitation traces to projections reaching the rostral ventrolateral medulla and spinal cord intermediolateral cell column.
Intranasal Orexin-A reduces wake-REM transitions in narcolepsy patients and produces significant sympathoexcitation in healthy humans. Both human studies used ~1,549–1,781 mcg (435–500 nmol) intranasally. No published human data exists below ~1,500 mcg for CNS wakefulness effects.
PMID 24406723 (Barateau 2013, n=12 narcolepsy type 1, 435 nmol IN, fewer wake-REM transitions, improved divided attention); PMID 35044844 (Trinder 2022, n=10 healthy lean males, 500 nmol IN, significant MSNA/sympathoactivation)
Only 2 published human studies with exogenous intranasal orexin-A peptide (n=10–14 each, single-dose crossover design). No multi-week dosing protocol in humans. SC route has no demonstrated CNS efficacy due to BBB impermeability of the 33-AA peptide. No approved human therapeutic protocol exists for the native peptide. Research field has pivoted to small-molecule OX2R agonists.
Extremely thin adoption. High conceptual interest but minimal documented self-use. Fewer than 50 dedicated Reddit threads. Community doses (10–50 mcg SC or intranasal) are 30–178× below published human CNS-active doses and likely produce no meaningful wakefulness effect.
Science requires ~1,500–1,800 mcg intranasally for any documented CNS wakefulness effect in humans. Community protocols use 10–50 mcg: 30–178× below published human doses. Community doses may be tolerable but have no evidence of efficacy. Research field has moved to small-molecule OX2R agonists (oveporexton FDA Priority Review Feb 2026), making the native peptide increasingly niche.
| Level | Dose / Injection | Frequency |
|---|---|---|
| Beginner | 10mcg | Daily |
| Moderate | 30mcg | Daily |
| Aggressive | 50mcg | 2x Daily |
Orexin-A comes as a lyophilized powder. Reconstitute a 1 mg vial with 2 mL bacteriostatic water. That gives you 500 mcg/mL, or 5 mcg per unit on a 100-unit insulin syringe. At the community starting dose of 10 mcg, that's 2 units drawn into a syringe and loaded into a nasal spray device. At 30 mcg, draw 6 units; at 50 mcg, draw 10 units. The reconstitution step matters more here than with most peptides. Orexin-A has two disulfide bonds and an N-terminal pyroglutamyl modification. Shaking the vial can break disulfide connectivity and destroy bioactivity. Add bacteriostatic water slowly down the vial wall. Swirl gently. Never vortex. Morning dosing only. This peptide activates every arousal circuit in the brain. Afternoon or evening use at any effective dose is asking for insomnia. One more thing worth knowing: community doses (10-50 mcg) are 30-178x below the only human doses that showed CNS effects. Published human studies used ~1,550-1,780 mcg intranasally. At that dose, a 5 mg vial gives you roughly 2.8 doses at ~$32 each from consumer sources.
Cycling recommendations are extrapolated from general neuropeptide research protocols. Due to receptor desensitization potential at OX1R and OX2R, periodic off-periods are advisable. No human clinical cycling data exists for the native peptides.
OX1R and OX2R are G-protein-coupled receptors subject to homologous desensitization via GRK phosphorylation and beta-arrestin-mediated internalization with repeated agonist exposure. No human cycling data exists for exogenous orexin-A. The 4 weeks on / 2 weeks off protocol in peptides.ts is extrapolated from general neuropeptide research conventions.
Or use the universal Peptide Calculator for any peptide.
Expected: Reduced wake-REM transitions and improved divided attention in narcolepsy (PMID 24406723). Significant MSNA increase and sympathoexcitation in healthy subjects (PMID 35044844): both wakefulness benefit and cardiovascular adverse effect are expected.
Monitor: BP and HR monitoring required at this dose range. Significant sympathoexcitation demonstrated in healthy lean males. Contraindicated in hypertension, cardiovascular disease, or arrhythmia.
Inject slowly down the inside wall of a 1 mg Orexin-A lyophilized vial. Do not shake. Swirl gently until the powder dissolves completely. This gives a concentration of 500 mcg/mL (5 mcg per unit on a standard 100-unit insulin syringe).
30 mcg = 6 units. 50 mcg = 10 units. Use a 29-31 gauge insulin syringe for measurement accuracy.
For intranasal delivery (the preferred research route): transfer the measured dose into a nasal atomizer or mucosal atomization device. Tilt your head slightly forward. Spray into one nostril while gently inhaling. Alternate nostrils between doses.
For subcutaneous injection (peripheral effects only, no expected CNS penetration): inject into the abdominal area. Rotate sites. Note that the full 33-amino-acid peptide does not meaningfully cross the blood-brain barrier from systemic circulation.
Orexin drives wakefulness; afternoon or evening dosing at any CNS-active level risks insomnia.
Check blood pressure and heart rate before your first dose and 20-30 minutes after. Any systolic rise above 20 mmHg or sustained heart rate above 100 bpm warrants dose reduction.
Use within 14 days. Do not freeze reconstituted solution. Protect from light.
Published human doses ~1,549–1,781 mcg (435–500 nmol). Community conservative: 10–50 mcg (likely sub-pharmacological).
CNS delivery confirmed via olfactory-trigeminal pathway in primates (PET imaging, ACS Chem Neurosci 2018). Requires intranasal delivery device. Consumer nasal spray adapters vary in droplet size and delivery efficiency, affecting CNS bioavailability at a given dose.
No established dose. The full 33-AA peptide is too large for significant BBB crossing from systemic circulation.
SC may produce peripheral orexin receptor effects (appetite stimulation, autonomic tone) but will not generate CNS wakefulness or arousal. Community 10–50 mcg SC has no documented CNS efficacy. Not appropriate as the primary route for any wakefulness indication.
Nanomolar quantities sufficient due to direct CNS delivery: not relevant to peripheral dosing contexts
ICV is the standard delivery method in rodent orexin circuit research. Not applicable to self-administration.
Community AM cognitive + wake stack. Semax provides nootropic/BDNF effects; Orexin-A theoretically adds arousal stabilization. Non-overlapping mechanisms. No interaction data.
Experimental chronobiology cycling stack: Orexin-A AM for wakefulness support, DSIP PM for sleep quality restoration. Theoretically complementary but no clinical basis: community speculation only.
Direct pharmacological opposition. DORAs block OX1R/OX2R: the same receptors exogenous Orexin-A activates. Co-administration produces mutual antagonism and negates both agents.
Do not combineAdditive sympathoexcitation. Modafinil activates endogenous orexin neurons upstream; exogenous Orexin-A acts directly on OX1R/OX2R downstream. Combined arousal and cardiovascular strain. No interaction data; caution warranted.
Additive sympathoexcitation and CV strain. Significant MSNA increase already demonstrated with Orexin-A alone at published doses (PMID 35044844). Stimulant combination poses meaningful cardiovascular risk.
Do not combineMay mask orexin-mediated cardiovascular sympathoexcitation signal, potentially obscuring a dose-limiting adverse effect marker.
Pricing updated 2026-04-09
Significant sympathetic nerve activation is the primary safety concern. Trinder's 2022 pilot study (n=10 healthy lean males)[2] showed marked muscle sympathetic nerve activity increases at 500 nmol intranasally. That translates to raised heart rate, blood pressure rises, and cardiovascular strain at pharmacologically active doses. This is not a theoretical risk; it was measured directly in healthy subjects. The human side-effect profile beyond those 22 total subjects is unknown. Preclinical data fills some gaps but carries the usual species-translation uncertainty. In animal models, higher-dose intranasal Orexin-A produced increased locomotor activity, tachycardia, and transient blood pressure elevation. Central administration at supraphysiological doses triggered anxiety-like behavior and stress-axis activation through corticotropin-releasing hormone signaling. These findings are consistent with orexin's known role as a sympathoexcitatory neuropeptide. Appetite stimulation is a predictable pharmacological effect. Orexin was literally named for appetite (Greek "orexis" = appetite). If you're using this peptide and noticing increased hunger, that's the drug doing what the molecule does. Insomnia from mistimed dosing is a real risk at any CNS-active dose. Orexin neurons are maximally active during waking hours. Any dose given after noon that actually reaches the brain could delay sleep onset or fragment sleep architecture. Injection-site irritation has been reported in animal subcutaneous studies. Intranasal administration carries the usual local effects: nasal irritation, mild burning, and congestion. Orexin neurons interact with monoaminergic, cholinergic, and histaminergic arousal systems. The potential for excessive arousal when combining with stimulants (modafinil, amphetamines) or other sympathoexcitatory agents is not a small concern. Contraindications include uncontrolled hypertension, cardiovascular disease, arrhythmia, severe anxiety disorders (orexin may activate the HPA axis), concurrent orexin receptor antagonists (pharmacological opposition), and pregnancy or breastfeeding (zero safety data). Stop use immediately if blood pressure rises more than 20 mmHg systolic post-dose, heart rate exceeds 100 bpm sustained, or you experience chest tightness, panic symptoms, or significant anxiety.
Verify Orexin (Hypocretin) dosing and safety with a second opinion
Orexin-A (33 AA, two intramolecular disulfide bonds, N-terminal pyroglutamyl modification) is structurally one of the more complex peptides in the research chemical market. Correct disulfide bond formation is essential for OX1R/OX2R binding: a misfolded or reduced peptide is biologically inert. Most consumer-grade suppliers lack mass spec verification for correct disulfide connectivity. Shear-induced unfolding during reconstitution is a real degradation pathway.
| Test | When | Target |
|---|---|---|
| Blood pressure (seated, resting) | Before first dose; 20–30 min after dose during first week at any new dose level | <130/85 mmHg pre-dose; >20 mmHg systolic increase post-dose warrants dose reduction |
| Resting heart rate | Alongside BP monitoring after each dose in first week | 55–80 bpm pre-dose; sustained >100 bpm post-dose warrants dose reduction |
| Subjective wakefulness / Epworth Sleepiness Scale (ESS) | Baseline and weekly throughout protocol | ESS score reduction ≥3 points from baseline indicates meaningful wakefulness improvement |
Significant MSNA and sympathoexcitation demonstrated in healthy humans at published doses (PMID 35044844). Baseline hypertension, cardiovascular disease, or arrhythmia are contraindications.
Orexin sympathoexcitation includes cardiac acceleration. Tachycardia is an early cardiovascular signal.
Validated self-reported measure of daytime sleepiness. ESS reduction would be the primary efficacy endpoint. In narcolepsy: CSF orexin-A <110 pg/mL is a clinical diagnostic marker but not accessible for self-monitoring.
Baseline assessment; initial tolerability evaluation in research protocols
Observable changes in wakefulness duration and sleep-wake consolidation in animal models
Peak effects on alertness, locomotor activity, and feeding behavior noted in preclinical studies
Assessment of sustained efficacy and potential receptor desensitization; cycling off-period may begin
Day 1, first dose: At published human doses (~1,550-1,780 mcg intranasal), expect rapid sympathetic activation within 15-30 minutes. Plasma tmax is roughly 15-30 minutes based on primate PK data, and the half-life is about 30 minutes, so acute effects are transient. In the Barateau narcolepsy study, wakefulness improvement appeared at this timepoint; in Trinder's healthy-subject pilot, sympathoexcitation was the dominant signal. At community doses (10-50 mcg), most users report nothing perceptible, consistent with the sub-pharmacological dose range. Nasal irritation and transient raised heart rate or blood pressure are the main acute side effects at higher doses. Weeks 1-2: No multi-week human data exists at any dose. Animal models showed sustained wakefulness consolidation with repeated dosing, but the receptor desensitization timeline at OX1R and OX2R in humans is unknown. Most community members report dropping the protocol by week 2 because nothing is happening at 10-50 mcg doses. Weeks 3-4: This is the theoretical peak protocol window, though no human data defines it. The community standard of 4 weeks on, 2 weeks off is borrowed from other neuropeptide cycling conventions. It is not based on any orexin-specific evidence. Off-cycle (weeks 5-6): The receptor recovery period. GPCR upregulation during the agonist-free interval is the theoretical rationale. No withdrawal or discontinuation effects have been reported at community doses, which makes sense if the doses never engaged receptors meaningfully in the first place.
At published human doses (~1,550–1,780 mcg IN): rapid sympathetic activation within 15–30 min. Plasma tmax ~15–30 min (primate PK). Half-life ~30 min: acute effects are transient. Wakefulness improvement in narcolepsy patients; sympathoexcitation in healthy subjects.
At community doses (10–50 mcg): most users report no perceptible effect: consistent with sub-pharmacological dose range. Occasional placebo-level mild alertness reported.
No multi-week human data. Animal models show sustained wakefulness consolidation with repeat dosing. Receptor desensitization timeline at OX1R/OX2R unknown in humans.
Most community members report abandoning protocol by week 2 due to perceived lack of effect at sub-pharmacological doses.
No human multi-week data. Theoretical benefit window before receptor desensitization; no data to define this timeline for the native peptide.
4 weeks on / 2 weeks off is the community standard, extrapolated from other neuropeptide protocols: not from any orexin-specific data.
No human data. GPCR upregulation expected during agonist-free period: the theoretical basis for cycling.
No withdrawal or discontinuation effects reported at community doses, consistent with sub-pharmacological (likely non-receptor-engaging) use.
Source: Kastin AJ, Akerstrom V. Orexin A but not orexin B rapidly enters brain from blood by simple diffusion. J Pharmacol Exp Ther. 1999;289(1):219-223. PMID: 10087007
Loading the interactive decay curve.
Orexin-A and Orexin-B are classified as research-only peptides. No orexin agonist peptide has received FDA approval for human therapeutic use. They are not scheduled substances under the Controlled Substances Act and can be legally purchased for research purposes in the United States. The orexin system itself is a validated pharmaceutical target. Suvorexant (Belsomra, FDA-approved 2014) and lemborexant (Dayvigo, FDA-approved 2019) are orexin receptor antagonists approved for insomnia treatment. The small-molecule OX2R agonist oveporexton received FDA Priority Review in February 2026 for narcolepsy treatment. WADA status: orexin peptides are not specifically listed on the World Anti-Doping Agency prohibited list, though athletes should verify current status before use given the evolving regulatory landscape for peptides in sport. The native peptides are sold by research chemical suppliers and are not manufactured under pharmaceutical-grade GMP conditions. Purity verification through CoA review (HPLC and mass spectrometry confirming correct MW of ~3,562 Da) is advisable. This content is for educational and research reference only. It does not constitute medical advice, and no physician-patient relationship is created by reading it.
Peptide Schedule Research TeamReviewed Apr 20267 Citations
