Detailed Explanation
Neuropeptide pair — orexin-A (33 amino acids) and orexin-B (28 amino acids) — produced exclusively by a small cluster of neurons (~70,000) in the lateral hypothalamus. Orexins are master regulators of the sleep-wake cycle, arousal, appetite, and reward.
Loss of orexin-producing neurons causes narcolepsy type 1, characterized by excessive daytime sleepiness and cataplexy (sudden muscle weakness triggered by emotions). Dual orexin receptor antagonists (DORAs) — suvorexant (Belsomra), lemborexant (Dayvigo) — are FDA-approved sleep medications that block orexin signaling to promote sleep. Orexins were independently discovered by two groups in 1998: de Lecea et al. named them 'hypocretins' and Sakurai et al. named them 'orexins.'
Key Facts
- Neuropeptide pair — orexin-A (33 amino acids) and orexin-B (28 amino acids) — produced exclusively by a small cluster of neurons (~70,000) in the lateral hypothalamus.
- Orexins are master regulators of the sleep-wake cycle, arousal, appetite, and reward.
- Loss of orexin-producing neurons causes narcolepsy type 1, characterized by excessive daytime sleepiness and cataplexy (sudden muscle weakness triggered by emotions).
- Dual orexin receptor antagonists (DORAs) — suvorexant (Belsomra), lemborexant (Dayvigo) — are FDA-approved sleep medications that block orexin signaling to promote sleep.
- Orexins were independently discovered by two groups in 1998: de Lecea et al. named them 'hypocretins' and Sakurai et al. named them 'orexins.'
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