Is a poor night watchman, say

• Misses part of a movie, maybe
• Drifts off for a bit
• Levels, informally
• Sleeps for a spell
• Goes to sleep
• Isn't with it
• Takes a catnap
• Catches a few Z's

Wiktionary Word definitions in Wiktionary
n. (plural of doze English) vb. (en-third-person singular of: doze )