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Pick up to three peptides to see how their mechanisms, studied uses and evidence levels differ. Rows where the entries disagree are marked with a blue edge.
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Comparison
Orexin A (hypocretin-1)
Cognitive & neuro
Evidence level
Limited evidence
Approval status
Investigational
Mechanism of action
- 1.Activates OX1 and OX2 G-protein coupled receptors.
- 2.Excites histaminergic, noradrenergic and cholinergic arousal systems.
- 3.Stabilises the sleep-wake switch so wakefulness does not collapse into sleep.
- 4.Links metabolic state to alertness, rising with fasting and activity.
- 5.Poor brain penetration from the blood limits any practical delivery.
Studied for
- Alertness and vigilance under sleep deprivation
- Narcolepsy research
- Cognition during sleep loss
- Reward and motivation circuits
Reported effects
- Small intranasal trials reported improved vigilance or reduced sleepiness in some measures
- Results are inconsistent and samples tiny
- Peripheral effects such as raised blood pressure appear before brain effects
Side effects
- Insomnia and difficulty sleeping
- Raised blood pressure and heart rate
- Anxiety at higher exposure
- Nasal irritation
Research protocol
Research context only - investigational. Human intranasal studies used single doses in the region of 0.3 to 1 mg and measured vigilance and sleepiness for several hours; animal work used central injections in the nanomole range. No repeated-dose human protocol exists.
Research context only
Evidence justification
A few very small intranasal studies in humans, alongside strong mechanistic and genetic evidence from narcolepsy research.