The "pillow sword" is an ancient practice, but there's always a trade off between instant operability and safety. The unsheathed small sword under your pillow is instantly ready when you grab it. BUT, that also means there's a foot or so of sharpened blade within inches of your throat while you sleep.....
The way I've always looked at it is that any of the common reasonable practices will do fine. Including empty chamber, or in a holster etc. Simply put, you need to be awake enough to know what you need to shoot at, (if you do need to shoot) and that should also mean you're past the point of groggy blind reaction.
If you're the kind of person who actually might grab a gun and pull the trigger before you know what you're doing, then I think the answer is not a holster or an empty chamber or a safety in the "on" position, I think the proper thing is for you to let someone else take care of gun handling and defense.
But that's just my opintion, and worth what you paid for it. IF you don't have that option, then you might consider a DA revolver and leave the cylinder open, or an SA with the loading gate open. In both cases, it can be shut as you pick up the gun, and open, prevents the gun from firing. For Semiauto, mag loaded chamber empty. If you're awake and alert the gun can be ready in an instant and if you're not awake and alert you aren't going to accidently shoot anyone...
Do what you think is right and the best for you. I'll pitch my tent on the other side of the hill from yours, (just in case) thank you!