When your child cries in fright during the night, don't assume it's a scary dream. There's another kind of event that can wake preschoolers called night terrors.
Night terrors occur when a child moves from deep sleep to a lighter sleep, usually between 10 p.m. and midnight. Your child may sit up in bed and scream or fling himself around, sweating and breathing hard. Even though his eyes are open, he won't be awake or responsive to you. In fact, it's often difficult to wake someone in the middle of night terrors, so don't try. Just stay with him to make sure he's safe. He won't even remember the episode the next day. (In comparison, nightmares happen in a stage of light sleep later on, often in the early morning. Children may cry or call for help. They may run into your room, sharing details of the horrible monster that was chasing them. Or they may not be sure what upset them. With a little comforting, they'll usually relax.)
Night terrors run in families, and children who are overtired or agitated are more susceptible. Most outgrow the episodes in the early elementary years.
Rosie seems to be having these lately. Frequently just as I'm getting ready to go to bed she'll start thrashing around. Sometimes she kicks the wall. Sitting with her and shushing her or rubbing her back sometimes seems to help. Sometimes I'll just go sit or (if I'm really tired) lie down with her to make sure she doesn't fall off her bed.
It's hard not to be disturbed when she seems so distressed in her sleep, but yeah, even if I pick her up and move her away from the edge of the bed, or if she suddenly sits up, she doesn't wake up most of the time.