Table 1.

Scoring criteria of the arousal stability index.

Scoring criteria	Score
>2/3 of all segments classified as 0 or A1	8
≥2/3 of all segments classified as 0 or A1, A2, A3	7
≥1/3 of last 160 s classified as B1	6
≥1/3 of second 160 s classified as B1	5
≥1/3 of first 160 s classified as B1	4
≥1/3 of last 160 s classified as B2/3	3
≥1/3 of second 160 s classified as B2/3	2
≥1/3 of first 160 s classified as B2/3	1

The arousal stability index quantifies the extent of the arousal regulation. This index was developed by the VIGALL research group (11); lower values mean earlier arousal decline.