White noise

I used to dismiss this as a bunch of BS, but seriously, I never wake up during the night anymore (except for Moppy or Poison next door, or someone getting up in the middle of the night). I don't hear the noise from the highway which I live off of anymore. Many mornings I don't hear my sister's alarm at 4:45a.m. I don't hear sirens. I sleep through the entire night, and have since August or so. What is my white noise of choice? My air filter. After I spend some time each night trying to get used to its hum and convince my brain that it is not detracting from my sleep, it isn't a big deal, and I can sleep with it on. It is so great to sleep the entire night.