Though most cases of sleep deprivation in horses has been labeled as narcolepsy, The Horse argues that in most cases it is not actually narcolepsy that the horse is suffering from.

 In fact, the tests often used to diagnose narcolepsy in horses—the physostigmine challenge used to induce narcolepsy in dogs or testing cerebrospinal fluid for the neuropeptide hypocretin, for ­instance—are unlikely to work in horses. In addition, many sleep deprivation cases respond well to management changes that impact behavior, as well as to pain medications. Narcolepsy would respond to neither.