Have you ever tried to FORCE yourself to go to sleep? It just doesn't work.
In fact, when you are so stressed about not being able to sleep -- or suffering from true insomnia, I recommend doing anything but trying to fall asleep so that for the time being you can simply relax and take the pressure off yourself. Do anything but trying to sleep. Read a book, write a letter, draw a picture, whatever. Just take the pressure off for a second and then you can try it again later.
I figure that trying to force yourself to fall asleep is like when you overthink anything in life: All it does is drive you crazy and you end up running in circles in your head over why you're not able to do the thing you so desperately want to do.
Over the years, there is one trick that has worked for me, though. I learned it when I started getting into hypnosis and guided meditation.
Here it is:
If you imagine that you are going down a stairwell (you can picture it anyway you want: white and filled with clouds or velvety and plush or even rustic and filled with trees), for some reason the exercise calms your brain sufficiently to allow you to drift off, stress-free, into unconsciousness. For the most part, this mental picture has never failed me in helping me fall asleep. Sure, maybe it doesn't happen instantly, but the mental imagery mimics hypnosis in a way that allows my brain to escape from recycling the day's events or the future's problems and just releases me into a relaxing descent.
Other sleepy tips I like: any kind of scent of lavender, "Sweet Dreams" essential oil, doing reiki on myself, holding or petting my dog and if I want to mix up the mental imagery: picturing I am going room to room exploring an old house where I have lived. Sometimes I enjoy simply praying to relatives who have passed away or picturing them with me and at peace. Or I concentrate on sending love out to various people (including those I've quarreled with, which is very freeing and cleansing and relaxing).
Do you have any sleepytime tricks? Oh, that reminds me: Sleepytime Tea actually works! Especially the kind with extra valerian root.
How do you go to bed and ensure you actually fall asleep?