A number of "household" remedies have been mentioned.
Basically, eating something that'll cause the digestive system to kick in coincidentally reduces the flow of oxygenated blood to the brain (hmmm ... that's enough out of you, Cliffy!)
A bowl of cereal was often recommended, however a professional nutritionist recently told me it's not the best (ditto for another version I heard in England - a spoon of peanut butter).
The downside to this method is that the food "lies on your stomach" ... so, it's a trade-off between getting some sleep while simultaneously adding to your hibernation layer ... or ...
Some other professional advice I received could best be summarised as "distraction" - as also mentioned, if there's something on your mind that's keeping you awake you can either deal with it, or not (and, yes - this can be problematic when it's something in your subconscious ... since it's therefore harder to deal with if you can't immediately put a finger on what's bothering you ...).
Thus, reading a boring book is okay (a variation upon "counting sheep"), except that it tires your eyes (ditto for watching TV) - there's also the danger of reading/watching something that's interesting which keeps you up (shut up, Cliffy - no sheep jokes ...)
There are tons of traditional/conventional relaxation techniques - "visualising" yourself asleep; starting with your toes, then your feet, ankles, calves. etc. (again, a variation upon counting sheep).
Another interesting one was to keep your eyes wide open as long as you could - staring - until it was impossible to keep them open (then, when your eyes were recovering/jammed shut ... sometimes it "forced" you to fall asleep) - it worked when I was younger (and carefree), but I haven't bothered with it lately.
Whatever you do - don't think that weight-lifting/the exercise bike/whatever and tiring yourself out will help (i.e. not at zero dark thirty). You'll only wake yourself up, run the risk of waking up other people.
Alcohol is a personal choice, but it's a depressant - and, I've seen too many lives ruined by it.
Exhaustion seems to work the best - I've always been able to sleep well on operations or exercises, and even when I'd only get two or three hours of sleep ... they were excellent quality (!)
Finally, I've found that Army.ca (and the Internet in general) doesn't help me get to sleep - so, one IA and Stoppage is to log off ... which is what I'm going to do now ... !
Sweet dreams, everybody! ^-^