ABSTRACT
In comparison with Narcolepsy, Idiopathic Hypersomnia stands as a relatively recently identified disorder and, in contrast with it, as a disease with a less accurate clinical and biological picture. An almost pathognomonic symptom such as cataplexy is not part of the clinical features and characteristic biological markers such as sleep onset REM periods (SOREMPs), HLA-DR2/DQB10602 association and undetectable hypocretin-1 levels in the cerebrospinal fluid (CSF) are lacking. Finally there is no natural animal model comparable to the narcoleptic dog. This is not to say, however, that the condition should not be considered. Indeed idiopathic hypersomnia is a debilitating disease. Delineating the frontiers between narcolepsy and idiopathic hypersomnia is of definite interest for the understanding of the two conditions. Pathophysiology is still almost totally unknown.
