Can I start yelling in my sleep?
Why would you choose to yell at night?
Because it makes me feel safe. I can avoid nightmares if I'm awake when they happen.
You may be having trouble with nightmares, but yelling won't solve it and its not okay to make alot of noise at night. Making lots of noise at night can bring the cops around to your house.
That's fine. If cops were to come, I might scare them away by screaming.
Nightmares and night terrors can both be awful to deal with, rarely leaving you time to get any actual sleep. But, trying to control how you wake up by yelling isn't going to work, you should ask for a sleep study and the doctors might find out the cause for the nightmares and offer you some coping mechanisms.