I want to understand and help my tormented boyfriend

Hi there.

-I made this account specifically to look for help from people who suffer from sleep disorders everyday. As the title says, the person I love the very most has terrible, vivid and disturbing nightmares. This week, he's has them every night. Usually, he has one nightmare every week.
-They are usually very disturbing, and he begs me not to make him talk about them. One example is he was running from a murderer with a gun, who shot him in the back. He ran into the elevator doors in front of him, and fell down the shaft into a meat grinder. Along with this, he experiences sleep paralysis.
-As a child, he suffered from night terrors. He is taking no medication at the moment.
-Please, tell me what I can do to help him. Making sure our room is quiet? How do I talk to him about this? What would comfort him? I have no clue where to start, and it's heartbreaking to watch him go through this