I know I haven't been formally diagnosed with aspergers but I have noticed since coming on this forum, searching and my cousins behavior that i actually have a lot of autistic traits.
That's where I saw "stimming"
As a kid I used to love spinning, love spinning objects. I'm not sure whether you'd say nail biting is a stim, but i've continued that since I was about 5 (I'm 16 and my nails are basically ruined). I also scratch my knuckles with my nails repeatedly until it bleeds, I used to get in a lot of trouble with opening and closing doors repeatedly when I was stressed and randomly turning lights on and off because I found it "fun", I still do, lol. One sub-conscious, but the most conscious, is listening to the same part of a song over and over. I didn't actually realize some consider this as a "stim" but it now makes sense.
So, why am I stimming so much? I have to do the majority of the list above in order to reach my expectation of "happy" else my day would just be wrong.