What is the history of Idiopathic Hypersomnia?

Prior to the use of polysomnographic studies, idiopathic hypersomnia (IH) was usually misdiagnosed as narcolepsy. Dement and colleagues first proposed that a diagnostic category other than narcolepsy should be used for patients who have excessive daytime sleepiness but do not have cataplexy, sleep paralysis, or sleep onset rapid eye movement episodes (Dement et al 1966). Subsequently, various labels were proposed to designate this entity: essential narcolepsy (Berti-Ceroni et al 1967), non-REM sleep narcolepsy (Passouant et al 1968), hypersomnia (Rechtschaffen and Roth 1969), hypersomnia with sleep drunkenness (Roth et al 1972), idiopathic hypersomnia (Roth 1976), idiopathic central nervous system hypersomnia (Anonymous 1979), and again idiopathic hypersomnia (American Sleep Disorders Association 1990). The previous sleep disorders classification parsed idiopathic hypersomnia into 2 categories based on sleep duration. Idiopathic hypersomnia with long sleep time (> 10 hours) entails excessive sleepiness with prolonged, unrefreshing naps lasting up to 3 or 4 hours, major sleep episodes of at least 10 to 14 hours in duration with difficulty waking up or sleep drunkenness, and no cataplexy. Idiopathic hypersomnia without long sleep time (< 10 hours) reflects excessive sleepiness and unintended, unrefreshing naps, with the major sleep episode lasting less than 10 hours, with difficulty waking up or sleep drunkenness, and no cataplexy (American Academy of Sleep Medicine 2001). The 3rd edition of the International Classification of Sleep Disorders (ICSD-3) no longer dichotomizes idiopathic hypersomnia based on sleep duration, suggesting a belief that this may be a single, heterogenous condition (American Academy of Sleep Medicine 2014).

Idiopathic hypersomnia is not easy to diagnose at early stages, as other conditions have to first be ruled out. When patients are finally diagnosed with the condition, they may have had it, historically, for many years.