My husband flew out of town on business last night, so I had to fall asleep without the sound of him breathing on the other side of the bed. (I always fall asleep after him. I sometimes suspect that he actually loses consciousness while brushing his teeth and just sleepwalks into the bedroom.) Sometimes his breathing gets so loud, almost snoring, that I want to smack him until he quiets down (as if that would actually help anything), but it does provide a bit of white noise to cover assorted distracting night sounds. I ended up turning my clock radio on with its sleep timer and drifted off as it played.
It's amazing how much you can ignore if you know there is someone else around. The heating system in our house gets rather noisy sometimes and sounds like someone is walking around in the next room. When my husband is home, I assume that the racket is caused by him walking around and it barely registers with my conscious mind. When I am alone, I find myself startled by those sorts of sounds. I know it is the heating system, but that knowledge does little to reassure the primitive, instinctive part of my mind until it has a little conference with the thinking part.
Instinct: What was that? Someone is in the house! Get ready to run away or fight or... Uh, what do you think it was, Thought?Silly brain! This provides yet another reason to get a pet someday. You can blame a lot of noises on a cat, just look at any stupid horror movie. *grin* Of course, we won't get a pet until we are living in a different house, which would probably have a quieter heating system.
Thought: Well, the last hundred times it was the heating system making the metal grate expand and sound like someone stepped on it, so I'm going to go out on a limb here and say "heating system".
Instinct: (reluctantly agreeing) Well, I'm not going to let down my guard until I listen to it for a while. I guess it could be the heating system again. You're so smart, Thought!
Thought: That's nice, Instinct. Now go back to sleep and let me read.