Interestingly, I’ve found that doing something like that, imagining a scene in which something is happening repetitively, really does work to send you off to dreamland. However it can backfire, because sometimes when you start running an image over and over in your mind, it gets stuck in a groove and actually prevents you from sleeping, the same way a fragment of music playing over and over in your head can.

Here’s a method that’s worked for me. I imagine I’m standing by a misty highway, waiting for a ride. I try to peer through the mist, to see the oncoming vehicle, I try to imagine a yellow taxi coming through the mist, and stopping and the door opens, and I climb in and we drive off through the mist.

This has successfully knocked me out on many occasions.

It’s all in your mind, you know.