TABLE 3 ] .

Clinical Features of the Narcolepsies and Idiopathic Hypersomnia

Feature	Narcolepsy Type 1	Narcolepsy Type 2	Idiopathic Hypersomnia
Excessive daytime sleepiness	Present	Present	Present
Cataplexy	Generally present (cataplexy plus characteristic MSLT features, or hypocretin deficiency, are necessary for diagnosis)	Absent (by definition)	Absent (by definition)
Sleep paralysis	Present in 69%a	Present in 35%a	Present in 20%a
Sleep hallucinations	Present in 77%a	Present in 42%a	Present in 25%a
Tetrad of all four of the above symptoms	Present in 42% (although not all present initially)24	Absent	Absent
Fragmented nocturnal sleep	Significantly lower sleep efficiency than narcolepsy without cataplexy25 or idiopathic hypersomnia26	May be common22	Not typical
REM sleep behavior disorder	Present in 45%-61%27; significantly more PSG-measured REM sleep without atonia than in IH28	Significantly more PSG-measured REM sleep without atonia than in IH28	Rate of REM sleep behavior disorder not studied
Sleep drunkenness	Rare, but occasionally reported26,29	May be common29	Common
Long nocturnal sleep times	Present in 18% of patients with narcolepsy with or without cataplexy30	Present in 18% of patients with narcolepsy with or without cataplexy30	Common
Effect and duration of naps	Refreshing, short		Unrefreshing (compared with either patients with narcolepsy with cataplexy31 or normal control subjects32), long

IH = idiopathic hypersomnia. See Table 2 legend for expansion of other abbreviations.

^aFrequency estimates for sleep paralysis and hypnogogic hallucinations are compilations from case series reporting on at least two of the groups outlined in this table.^29,33-38