Table 4.

Comparison of SSS and KSS.

Level	SSS	KSS
1	Feeling active, vital, alert, or wide awake	Extremely alert
2	Functioning at high levels, but not at peak; able to concentrate	Very alert
3	Awake, but relaxed; responsive but not fully alert	Alert
4	Somewhat foggy, let down	Rather alert
5	Foggy; losing interest in remaining awake; slowed down	Neither alert nor sleepy
6	Sleepy, woozy, fighting sleep; prefer to lie down	Some signs of sleepiness
7	No longer fighting sleep, sleep onset soon; having dream-like thoughts	Sleepy, but no effort to keep alert
8	—	Sleepy, some effort to keep alert
9	—	Very sleepy, fighting sleep