I've had sleep paralysis for a good 15 years now. I'd say I get them an average of once a month. In the beginning, it was terrifying. I would sleep with my head under the blanket or facing the wall and feared that I was stuck. Afraid that all I was going to see was what was in front of me. It's why I can no longer sleep in that way.
When I am sleeping with my eyes facing an open room, I would sometimes see a woman that looks old and has long hair covering her face. Her body mostly a black shadow. Similar to the movie "The Grudge". Which is why that movie haunted me for months. I watch a documentary on netflix a few years back about the paralysis, it's where I found out I wasn't alone in both the sleep and seeing the woman. Which is named The Hag.
Now in my older years, I am more annoyed by it than scared. I have full awareness of my state. I know that I am asleep but my body is going through the sleep paralysis. Having had it so much, I have trained myself to be able to wake up from the paralysis. I ignore the shadow woman I see and focus on the steps I do to wake. It's hard, but I manage to muster the strength to move either my foot or neck. It feels like lifting weights but enough movement from one or the other would wake me. I'm also able to force a scream which, in reality, sounds more like a whimper. Other option is if my wife is awake and laying next to me. Sometimes she would see my slight movements or hear my whimper. She then knows what I'm going through and wakes me.
My wife was the key to me being able to have some control over my state. I've told her about my problem. The first time she woke me up because she said I was acting strange in my sleep. From that moment, I would try different things and ask her what she can see, hear, or feel.
I hope you read this and give your friend this advice. If you have any questions, feel free to message me.