Ctrl+V from what I wrote in Candy Fair's thread:
Well maybe you do need professional help but in the meantime, I can offer some home remedies that may help you a little.
You may want to drink some hot/warm drinks before you sleep such as teas (without caffeine of course). Chamomile is good and helps relax. A little nutmeg doesn't hurt either. You could try drinking some warm milk with nutmeg.
You may also want to look into natural supplements such as Melatonin.
Try being active as much as possible during the day. Exercise a little at least once a day if possible.
Some breathing methods may help also, you might want to do some research on that.
Also you may want to cut out eating anything heavy especially closer to the time you sleep.
Hopefully those tips may help. There are a few other things I can't think of right now, but I'll come back later if I can think of them.
Oh, I thought I should mention, that if it is a pattern where you can't sleep and you lay in bed a long time and can't sleep, it is sometimes recommended that you get out of bed after 20 mins of not sleeping and do something. This way your brain doesn't see a pattern of "oh the bed and laying down is to stay awake". If you stay in bed and cant sleep and do that constantly, your brain will think that it is normal, and it will be harder for you to sleep. So it's suggested that maybe 20 mins you can't sleep and you have been in bed, get up and get active with something, such as reading, standing, or just walking around for a little and then try again.
Note: insomnia is a very very common thing. To add to that, there are very common and useful remedies.