I've found that self-relaxation techniques work really well for me, allowing me to sleep pretty quickly no matter how awake I am at the time (it helps if it's dark and quiet, though). What I do is imagine a mental needle/pin that I use to poke myself, starting up the right side of my body then progressing down and back up the left to the head. Each poke causes numbness/relaxation, and I find that by the time I'm back at the top, I'm almost asleep (sometimes it takes two rounds or more). I'm not into chakra or meditating or any of that, so I don't have to target the exact specific point each time, it's just my way of visualizing relaxing parts of my body until my whole body is relaxed. I used to imagine just relaxing body part by body part, but this works better for me. Sort of a mental anaesthetic.