Table 2.

Arousal Stability Score corresponding to occurrence of certain vigilance stages during a 15-min resting EEG.

Score	Stability Level (criterion)	Operational definition
11	Level 1: less than 1/3 of all segments not classified as 0/A- or 0/A1-stages	rigidity, only appearance of 0 and A1 stages
10		rigidity, only appearance of 0 and A stages
9	Level 2: at least 1/3 of all segments classified as B (B1 + B2/3)-stages	stage B emerged in minute 11–15
8		stage B emerged in minute 6–10
7		stage B emerged in minute 1–5
6	Level 3: at least 1/3 of segments classified as B2/3-stages	stage B2/3 emerged in minute 11–15
5		stage B2/3 emerged in minute 6–10
4		stage B2/3 emerged in minute 1–5
3	Level 4: occurrence of at least 1 C-stage	stage C emerged in minute 11–15
2		stage C emerged in minute 6–10
1		stage C emerged in minute 1–5