HCRT encodes the precursor protein for hypocretin neuropeptides (orexin-A and orexin-B), which are exclusively produced by neurons in the lateral hypothalamus 1. The precursor undergoes proteolytic processing to generate two bioactive peptides that bind to orexin receptors HCRTR1 and HCRTR2 1. These neuropeptides primarily function in regulating feeding behavior, with central administration stimulating food consumption and mRNA levels increasing during fasting states 1. HCRT also plays crucial roles in sleep-wake regulation and arousal, with hypocretin neurons driving cholinergic and monoaminergic activity across sleep cycles 2. The system receives circadian input from the suprachiasmatic nucleus, contributing to clock-dependent alertness 2. Disease relevance is most prominently demonstrated in narcolepsy, where loss of hypocretin-producing neurons causes excessive daytime sleepiness and cataplexy 2. Autoimmune mechanisms underlie narcolepsy pathogenesis, with hypocretin-specific CD4+ T cells detected in all tested patients and hypocretin-specific CD8+ T cells found in blood and cerebrospinal fluid 3. Additionally, HCRT gene expression can be epigenetically silenced by hyperglycemic conditions through histone modifications, though this silencing can be reversed by N-acetyl-d-mannosamine treatment 4. The neuropeptides also exhibit neuroprotective effects, with orexin-A reducing astrocytic inflammation and apoptosis in cerebral ischemia models 5.