being still half asleep; being half awake; being not yet quite awake
寝ぼけた顔で、おはよう。
Good morning, you look half asleep.
寝ぼけて塩と砂糖を間違えた。
Being half asleep, I mistook salt for sugar.
朝早く起こされ、まだ寝ぼけが残っている。
Woken up early, I'm still feeling drowsy.