I know people who do this. I think it's weird as fuck and give them shit for it, but as a collective of people that do it, they think they're normal. weirdos
I do that too. If I don't have some kind of drone to knock out with, my mind wont stfu and let me sleep. It's a lot healthier than falling asleep with the TV on, being unconsciously bombarded with advertisements from commercials.
It is very common for people suffering from tinnitus to sleep with some sort of audio stimuli (eg.a fan for example) as a way to mask the tinnitus noise and make it easier to relax.
I got a mini fridge in my bedroom so I have the same kind of noise going on.
At first when the fridge was new I couldn't get to sleep and almost threw it out again.
But after some time I got used to it and now when the fridge is off for some reason
I wonder how fucking silent actual silence is, haha!
In a similar vein, I have my iPhone running music really low at night... I generally can't sleep otherwise!
I like in winter having the heating on ever so slightly and hearing it through the vents... I sleep like a baby