Good idea, if your car keys have a remote alarm feature you have a perfect "panic button" set and ready to go when you hear things go "bump" in the night. Keeping a cell phone in the nightstand is also a good idea. Another good idea is to replace your bedroom door with a solid core door and use a dead bolt lock set.
I recently took the required training for Wisconsin's newly minted CCW law. The instructors threw out various home invasion scenarios. After discussion of the hypotheticals I asked the entire room how many people had a lock on their inside bedroom door. I was the only one, including the instructors!
Regards,
GtG
PS I have a "Tomcat" too but I would not bet my life on it, I would not go less then .380ACP for serious social engagements, 9x19mm much better.