Hypo-cretin neurons
The hypocretins also called the orexins are referred to as hypothalamic neuropeptides is thought to have quite an important role in the regulation of arousal states and sleep. As per researchers, in a human brain, there are only 10,000–20,000 orexin-producing neurons, which is situated predominantly in the lateral hypothalamus and perifornical areas. They are found to widely throughout the central nervous system, which actively regulates wakefulness, feeding, and other kind of behaviours. There exists only two types of orexin peptide and two different types of orexin receptor. The discovery was made in this area was reported independently by two groups using different techniques. The discovery of the orexins, orexin-A (Orx-A) and orexin-B (Orx-B), was done almost parallely by Sakurai et al.with the employment of the technique of orphan receptor cloning. The finding that the levels of cerebrospinal fluid (CSF) of these peptides were abnormal in patients who had narcolepsy stimulated research on the possible role of these peptides.