I either have to stim, hold or be held.
If my wife is spooning me, or if I'm holding her in some way while lying on my back, or if I'm holding one of teh kids, I can go right to sleep.
If I'm facing my wife, I stim on her. Like, last night I kept annoying her by tracing the lines where the light from the hall fell on her back and shoulders.
If I'm by myself, or I just roll over and stop bugging her, i have to mentally "stim", though I never really thought of it as that till this thread.
For some reason, militaristic images really relax me. I like to think of fighter jets, or Decepticon jets, or of helicopters, or of Storm Troopers, or of Storm Shadow, or of Cobra Vipers, or of tanks (regular tanks or HISS) tanks. As I'm drifting into thought, I'll start whispering whatever it is, and I"m usually asleep in a few moments.
BUt I think you just gave me a big answer to my lifelong insomnia: I need to stim to sleep!