Bad Dreams?

For the past few nights Jacob has woken up several times crying and his shirt is sweaty. He isn't too coherent when he wakes up and he doesn't talk very coherently or audibly. It takes comforting to get him to calm down and go back to sleep.  In the morning he doesn't really remember anything when we ask him about it. Last night I was finally able to get out of him that he wanted the bathroom light on because he was scared. He didn't know what he was scared of but he went back to sleep easily afterward and didn't wake up again. Not sure what is going on. It reminds me of when he was a baby and he would wake up crying and he would stare off at something with a blank look. It took calming him down and getting him back to sleep before he would snap out of it.