Further subdivision of those without cataplexy resulted in 2 clusters evenly mixing individuals with narcolepsy type 2 and idiopathic hypersomnia, which were separated on the basis of variables related to awakening (e.g., sleep drunkenness and subjective difficulty in awakening), sleep need (e.g., weekend-week sleep length difference), and objective biomarkers (HLA-DQB1*0602 positivity and hypocretin-1 level). This evidence concerns the gene HCRT and idiopathic hypersomnia.