ABSTRACT
There is now no doubt that hypocretin/orexin (Hcrt) deficiency is the cause of most narcolepsy in humans (1,2). It is also clear that mutations of the Hcrt system cause genetic narcolepsy in several animal species (3,4). Narcolepsy in these Hcrt deficiency situations is characterized by sleepiness during the normally active period and losses of muscle tone during waking periods called cataplexy. We know from observations in humans and in canine narcoleptics that such cataplectic episodes are accompanied by unimpaired consciousness, and it is reasonable to expect that this is also the case in rodent Hcrt mutant models.
