Sorry for this I am not experiencing it so maybe I'm completely wrong but these people seem to be overblowing this a lot. Health effects? I mean, it's a hum. Sure you can't find the source but heaters hum, ACs hum, cars going past hum, bass hums. Like how is it possible that it's this huge of a problem? When a humming stops I tend to actually miss it because it becomes too quiet. I tend to hear the air conditioners or heaters at work all day every day for at least 8 hours. Is this hum much much louder than that or what?
Speaking personally, noises that I can locate the source/direction of are easily ignored. Noises that sound the same in multiple locations/appear to be coming from everywhere are _much_ more annoying (I once had a fridge that produced a whine that was right of the cusp of my hearing -- both in volume and frequency -- and I must have spent a good 20 minutes tracking it down because it was impossible to ignore - it sounded the same from anywhere in the room until I got within a few inches of the source). If it's a noise similar to that, I can see it potentially effecting people's sleep and having knock-on health effect.
If it was louder, some may actually find it easier to ignore. I can sleep easily with either a quiet room or with a loud room fan on, but if there's just the fan noise from my NAS I find it much more difficult.
Good for you, but for some of us it will drive you nuts. The quieter it gets as you try to sleep, the louder the hum seems to get. And if you hear it more in one ear than the other, it feels like your head is warping from more pressure on one side than the other. Sure it's "all in your head", and just like with being a little too cold you could theoretically train yourself to ignore it. But that's easier said than done.
