I always have trouble sleeping too ... however the first thing I do is I get off of my PC. The second thing I do is lay down in bed. The third thing I do is close my eyes.
I recommend you get off of the internet, then lay down in bed, and third, close your eyes ... hopefully that wall be a good start
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OK seriously, take some Benedryl or Tylenol PM (it has benedryl in it) or something with Diphenhydramine in it. Usually with 2 benedryl tablets, I can go right to sleep in like 15-30 min.
If that is not available, drink a glass of whiskey, vodka, rum etc ... make it a big drink, but don't over-do it. You want it to hit you hard and fast .. but you don't want to be sick in the morning.
If you are a non-drinker, then try to void your mind of thoughts ... think about nothing, or think about the most boring thing you can think of ... hopefully that will do the trick