The Epworth Sleepiness Scale has been validated primarily in obstructive sleep apnea, though it has also shown success in detecting narcolepsy and idiopathic hypersomnia.[3] It is used to measure excessive daytime sleepiness and is repeated after the administration of treatment (e.g., CPAP) to document improvement of symptoms.[5] In narcolepsy, the Epworth Sleepiness Scale has both a high specificity (100%) and sensitivity (93.5%).[6]