I strongly suggest you remove the gun from your nightstand at this point, for your safety and the safety of others. When your PTSD is under better control, you can re-evaluate the need for it in the bedroom.

I also have a bad time at night. I leave a light on upstairs and downstairs and that helps; so does rigging up noisemakers on my doors (I hand keys from all the deadbolts so I'll hear them fall if the doors open). I also check all the windows and doors before going to sleep.

I hope your nights get easier soon.