I am fascinated by the subject of sleep and dreams. I hope that I have some time later in life to do some research and experimentation on this subject.
Luckily, I never have a problem falling asleep. I use the following three techniques and find them quite useful. While the first two are fairly common, I don't know any one who has tried the third - in fact I have not heard of it elsewhere. But it works for me unfailingly.
1. Progressive relaxation: This is similar to a technique used to enter shavasan, as far as I know. Start with the toes - tense them for a few seconds, relax them to the point that they no longer exist for you. Then the middle of the foot - tense and then relax and imagine it no longer exists. Then the back of the foot, the ankle, and so on up the body. By the time I get to the neck and start up the back of my head, I am so peaceful and relaxed that I fall asleep. I have NEVER finished the entire exercise and found myself awake. The sleep you get in this way is usually deep and restful.
2. Blackening out your vision: I close my eyes and then begin imaginarily layering black paint across the back of my closed eyelids starting at the top left. One band from left to right and the next band a little lower from right to left and then the next a little lower from left to right again and so on, a little like raster scanning in traditional CRT televisions and monitors. This too never fails to put me to sleep. The sleep is light though and it takes some time for you to fall into a deep sleep.
3. Flashing images ("Imagening"): This is my own invention and it works the fastest. I just close my eyes and generate random images in my mind - perhaps a crow, a book, a horse, a car - it is important that they are as randomly selected as possible, right at that point in time. I keep each image in my mind about 2-3 seconds, which gives my eyeballs some time to trace a part of its outline in the act of "seeing", then I just think of another image and "see" it in my mind for 2-3 seconds, then the next image, and so on. After perhaps the third or fourth image, the images start to flash involuntary (i.e. I am not consciously deciding which picture to flash next) and right away some dream plot begins to evolve and I am asleep... mostly in less than a minute, often in 15 or 20 seconds! This sleep is most dreamy although not very deep.
Do you have any favorite techniques of your own to fall asleep?