Creative relaxation
As a student I participated in national competitions in biology. During one of the related trips I visited some kind of training called "Creative relaxation". Now I don't remember many details about it, it was something hypnotic and meditative. Funnily it didn't seem to contain anything creative. I decided later that this was some yogi practice, because I found quite similar recording in a "Yoga" file on my friend's computer.
I learned something useful on this training. All participants got a kind of "psychological anchor": press your index finger on the thumbnail to restore that relaxed state. I forgot about it some years later, but recently recalled it and started using again. 15 years later it still works, i.e. helps to fall asleep. And I can even sleep on my back, something I could never do.