Table 1.

Proposed definitions of terms pertaining to hypersomnolence.

	Excessive daytime sleepiness (EDS)	Excessive need for sleep (ENS)
Clinical symptoms/complaints	[EDS/ENS] Feeling of sleepiness (as opposed to fatigue) for most of the day.
	[EDS1] Inability to stay awake in monotonous situations with unintended napping and possible sleep attacks.	[ENS1] An acquired increased need for sleep in normal daily life, including ≥10 h of sleep per 24 h and/or ≥ 9 h of nocturnal sleep.
	[EDS2] Acquired need for scheduled napping during the day.	[ENS2] In case of only minor complaints of sleepiness (i.e., [EDS/ENS]), daily occurrence of sleep inertia/sleep drunkenness.
	[EDS3] Difficulty with sustained attention and vigilance.	[ENS3] Sleep extension will not significantly improve the daytime complaints (i.e., [EDS/ENS] and [ENS2]).
	[EDS4] Automatic behaviours that can be attributed to EDS.
Diagnostic criteria	Daily or near daily occurrence of [EDS1] OR daily occurrence of [EDS/ENS] and ≥1 of the other symptoms listed (i.e., [EDS2–4]).	Daily or near daily occurrence of [EDS/ENS] AND [ENS1] AND [ENS2] AND [ENS3].

Definitions are adapted from [1].