National Sleep Foundation

Chapter 4: Hypersomnias

What is Idiopathic Hypersomnia?

Patients are diagnosed with idiopathic hypersomnia if they present with constantly severe EDS for at least 3 months without other defining features (e.g., REM sleep abnormalities). Frequent yet un-refreshing naps are common, as are difficulties in waking up and post-awakening confusion (sleep drunkenness). Simply increasing the total time spent in bed does not resolve the excessive daytime sleepiness. An increased amount of time spent asleep is not a feature of idiopathic hypersomnia.1


  1. American Academy of Sleep Medicine. International Classification of Sleep Disorders, 2nd ed: Diagnostic and Coding Manual. Westchester, Ill: American Academy of Sleep Medicine; 2005.