Studies comparing patients with narcolepsy type 1 with patients who are diagnosed with idiopathic hypersomnia, a neurologic disorder characterized by excessive daytime sleepiness but with normal orexin signaling, found that patients with narcolepsy type 1 have a significantly higher BMI and a larger waist circumference compared with patients with idiopathic hypersomnia (12, 16). Here, HCRT is linked to idiopathic hypersomnia.