I leave my Sig in the holster and set it on the night stand next to the bed. It is at eye level, in the holster, pointing away from me. Thus it is in a very natural position to just grab.
However, what I really expect to use if I have a middle of the night noise/intruder alert is a 12ga shotgun that is in the nearest closet leaning in the corner of that closet. The reason is, when I am awakened abruptly at 3am, my body is still groggy and my motor functions are not at 100% for a few minutes. Therefore a shotgun, with 00 buck allows me some leeway in my 'aiming' at any intruder. I have an inexpensive Chinese (Norinco) short barrel self-defense shotgun that remains in the closet. At less than $200, it works great (A knock off of the Remington 870), yet if stolen I am not out much money.