to cry out in one's sleep (e.g. from having a nightmare); to moan (in anguish) in one's sleep
子供が熱にうなされている。
The child is moaning in their sleep from a fever.
彼は悪夢にうなされて目が覚めた。
He was tormented by a nightmare and woke up.
怖い映画の後、時々うなされることがある。
After a scary movie, I sometimes moan in my sleep.