locking up is a good idea if children are in the house
A normal person is temporarily paralyzed by suppression of motor nerve impulses while dreaming. Rapid eye movement is the only external clue that one is dreaming. You may dream you're running an obstacle course, but your spouse won't feel you spazzing around in the bed.
I think there's no chance that I would fire a weapon while sleeping. Even so, I place my pistol so I must move to grab it, just to make sure I don't roll over on it and have an Unplanned Sleep Discharge or put a Glock-shaped dent in my back.