I did the same thing when I was that age and younger. I slept walk and had horrible night terrors. I woke up screaming and I never remembered it. You are doing the right things by having alarms. I can tell you what my parents did. Your results may vary. Try to reduce the child's stress level. You should start relaxation exercises every day. That can be as easy as breathing deeply while counting. If your child can focus on meditating that might work. I took up swimming. I don't mean just playing in the water but swimming laps in a pool. For some reason in elementary school doing laps twice a week helped me calm down. Also no electronics, ipads, TV, or video games after a certain hour. Having a TV as a night light can cause problems for anyone. After 8 or 9 it is time to read a book or just relax and lay down. The other option would be sleeping drugs but I am so against this for children. Please try other options first.
You are being a great father by getting up at night and making sure he is okay. Don't stop doing that.