I went through a period where I'd wake up aboud 2-3 hours after going to bed and couldn't get back to sleep for most of the night.
I used a related technique to help. I count backwards from 1000, and force myself to keep my eyes closed. It's a task that takes just enough brainpower that it's hard to do on autopilot while my mind drifts to something else. If I do wander off I just go back to counting whatever number I remember.
It's been almost totally successful in the 2 months I've been doing it.
My sister once taught me a small trick to calm myself down when I was anxious but had no idea what I was anxious about: Count down from a random 3-digit number, subtracting 7 at each count. (e.g. 794, 787, 780, 773, ...) Do it until I drift away and lose track, unable to continue.
It works. I guess it's kind of in that "takes just enough brainpower" league. This takes more brain power than simply counting down though, and I'm not sure if this actually helps one falling asleep...
Another technique I derived from this is to do a countdown in the foreign language I was learning. Several years ago it was in English, and right now it's in Japanese. It also takes more brain power than counting down in my mother tongue, with the additional benefit of getting a little bit of practice. Killing two birds with one stone I guess :p
I used a related technique to help. I count backwards from 1000, and force myself to keep my eyes closed. It's a task that takes just enough brainpower that it's hard to do on autopilot while my mind drifts to something else. If I do wander off I just go back to counting whatever number I remember.
It's been almost totally successful in the 2 months I've been doing it.