Try this:
Have Spouse/Significant Other/room-mate go into the easiest-to-break-into room, etc, and Shout "CRASH!", then begin walking to your location.
Meanwhile, you see if you can get your weapon, locate ammo, and get it ready to go BEFORE 'intruder' walks though the doorway and says "Bang! Bang! Bang! You are TOAST!"
Only try this with dummy ammo or 'snap caps' DO NOT USE REAL LIVE AMMO FOR THIS TEST.
You probably can be ready if you try this while fully awake. But add in the factors of having to wake up, determine that there is a real threat, and the clumsiness/lower alertness of sleep.....