What is here and what is not
Roughly seven hundred papers mentioning orexin are published every year. Almost none of them change anything for a reader following this drug class. This page is the small remainder, and the filtering is the point: a candidate list is generated from Europe PMC on a schedule, then read and cut by hand before anything is published.
What gets left out: papers where orexin appears once in passing, animal work that does not change the mechanistic picture, and trade press summarising a result this site already reports from its primary source. What gets included is listed with its limitations attached, including when the answer is that a study was done in mice.
Notes are written here. Abstracts, figures and tables are not reproduced; follow the DOI for those. Every entry links to PubMed as well, and open-access papers are marked so you know which ones you can read without paying.
Why the neurons are lost
Narcolepsy type 1 is caused by the death of a few tens of thousands of orexin-producing cells. What kills them is still argued about, and the argument is not settled by either of these papers.
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Narcolepsy is (not) an autoimmune disease
The autoimmune explanation for narcolepsy type 1 gets repeated as though it were settled. This review argues that it is not. Nobody disputes the genetic link to HLA-DQB1*06:02, and nobody disputes that the orexin neurons die. What has never been shown is that immune cells kill them. The authors lay out the alternatives, including the possibility that the immune response follows the damage rather than causing it, and that the mechanism is immune but is not cell killing. Read it against the Annals of Neurology report below, which found evidence pointing the other way.
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Increased numbers of CD4+ T-cells in the hypocretin/orexin region of narcolepsy type 1
Post-mortem brain tissue from people with narcolepsy type 1 held eleven times as many CD4+ T-cells in the orexin-producing region as control tissue did. CD8+ T-cells were not raised. Neither cell type was raised elsewhere in the hypothalamus or in unrelated brain regions, so the finding is specific to the place where the damage happens. The CD4+ cells carried tissue-resident memory markers, meaning they had settled in rather than passed through. This is the kind of direct human evidence the autoimmune argument has largely lacked. It still does not prove those cells did the killing.
What the system does
Orexin holds you awake. It also does other things, and the other things matter for a drug that raises orexin signalling across the whole brain.
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Therapeutic potential of targeting the orexin (hypocretin) system in sleep disorders
The single best starting point if you want one paper covering this whole field. It sets out how orexin signalling is lost in narcolepsy type 1, then asks the harder question of whether weaker or disrupted signalling also contributes to narcolepsy type 2, idiopathic hypersomnia and obstructive sleep apnoea, where the evidence is much thinner. It covers drug development running in both directions at once: the antagonists already approved for insomnia, and the agonists tracked on this site.
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Empathy and prosocial behavior powered by orexin-driven theta oscillations
In mice. Orexin neurons reaching the anterior cingulate cortex became active both when an animal watched another in distress and when it groomed that animal afterwards, but only in animals that had been through the same distress themselves. Switching those projections off with light suppressed the brain rhythm and the behaviour together. Nothing here bears on narcolepsy or on any drug in development. It is listed because it maps another job the orexin system does, and because coverage of results like this tends to drop the word mice somewhere between the paper and the headline.
Metabolism
Orexin acts on appetite, body temperature and energy use as well as on wakefulness. Narcolepsy carries a metabolic burden that no orexin agonist trial has yet been designed to measure.
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Narcolepsy and metabolic disease: a meta-analytic synthesis
Fifty-four studies pooled. Obesity was the most common metabolic comorbidity in narcolepsy at roughly 30% of patients, with diabetes, high blood pressure and abnormal blood lipids each near 10%. Results are broken down by narcolepsy type, age, sex, orexin deficiency, HLA status and whether patients were on treatment. This is the human-data answer to a question the mechanism raises: orexin does more than hold you awake, so if it is missing, more than wakefulness is affected. Whether restoring orexin signalling reverses any of this is unknown, and no trial in the current pipeline is designed to find out.
Diagnosis and measurement
Narcolepsy type 1 has a confirmatory test. Narcolepsy type 2 and idiopathic hypersomnia do not, which is why trials in those conditions are harder to design and harder to read.
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Skin thermal dynamics and hypothalamic thermosensitivity dissociate REM sleep and cataplexy in narcolepsy
Skin temperature dropped, and the gap between hand and trunk temperature widened, in the minutes before a cataplexy attack. The pattern appeared in both patients and orexin-knockout mice. The same signature precedes REM sleep, which cataplexy physically resembles. The authors then set out to test whether the temperature change drives the attack or merely accompanies it, which is the part of the paper worth reading in full. If the causal claim holds, it points at something a wrist-worn sensor could measure, in a field that currently needs an overnight laboratory study.
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Central disorders of hypersomnolence: a narrative review on current and potential biomarkers
Narcolepsy type 1 can be confirmed by measuring orexin in spinal fluid. Narcolepsy type 2 and idiopathic hypersomnia have no such test, and are diagnosed with the multiple sleep latency test, which does not reliably give the same answer twice in the same patient. This review surveys what might replace or supplement it across blood and spinal fluid markers, imaging and sleep recording. Useful background for why several programs on this site read out cleanly in narcolepsy type 1 and ambiguously everywhere else.
Beyond narcolepsy
Uses for orexin agonists outside the conditions this pipeline is aimed at.
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The role of danavorexton for perioperative opioid-induced respiratory depression and sedation: a narrative review
Danavorexton is the intravenous Takeda agonist that established the mechanism in humans and was then superseded by oral compounds; this site lists it under discontinued. The molecule did not disappear with the narcolepsy program. This review makes the case for it in a different problem: reversing the suppressed breathing and sedation that opioids cause after surgery. Naloxone already reverses opioid breathing suppression, but it reverses the pain relief along with it. An orexin agonist would raise respiratory drive and arousal without touching analgesia. It is a narrative review arguing a case, not new trial data.
The papers as data
This list is published as research.json under CC BY 4.0, the same terms as the pipeline data. Titles, authors, journals, dates, DOIs, PubMed IDs, open-access status and the notes written here. Use it and link back.
A paper that is later retracted or corrected does not quietly stay on this page. Everything cited here and on the program pages is re-checked against Europe PMC on the same schedule that finds new work.
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