Table 3.

Simplified overview of the American Academy of Sleep Medicine (AASM) (Berry et al., 2018) and World Association of Sleep Medicine (WASM) (Ferri et al., 2016) criteria for the identification of leg movements (LMs) and the definition of periodic leg movements (PLMs).

	AASM (Berry et al., 2018)	WASM (Ferri et al., 2016)
LM
Minimum duration	0.5 s	0.5 s
Maximum duration	10 s	None (but candidate LMs are those with a duration 0.5–10 s)
Timing of the onset	Point at which there is an 8 µV increase in EMG voltage above resting EMG	Point at which there is an 8 µV increase in EMG voltage above resting EMG
Timing of the ending	Start of a period lasting at least 0.5 s during which the EMG does not exceed 2 µV above resting EMG 8 µV above resting EMG for at least 0.5 s	Start of a period lasting at least 0.5 s during which the EMG does not exceed 2 µV above resting EMG
Minimum amplitude	NA	NA
Morphology threshold		The event contains a period ≥ 0.5 s with the median EMG amplitude ≥ 2 µV above resting baseline
PLM	At least 4 consecutive LMs	At least 4 candidate LM
Intermovement interval	5–90 s	10–90 s
End of PLM sequence	NA	Candidate LM intermovement interval < 10 s or > 90 s OR LM that are not CLM
Association with arousal	If they occur simultaneously, overlap, or when there is < 0.5 s between the end of one event and the onset of the other event	If they are overlapping or when there is < 0.5 s between the end of one event and the onset of the other event
Association with respiratory events	An LM should not be scored if it occurs 0.5 s preceding or following a respiratory event	Candidate LM that have some part overlapping with an interval of 2 s before to 10.25 s after the end of a respiratory event

CLM, candidate leg movement; EMG, electromyography.