What have you tried so far? I have always had issues falling asleep quickly, and I have a few tricks that seem to work well for me... double bonus, no drugs or docs involved.
~ Meditation: This does not need to be spiritual in any way... Focus on your breathing and clearing your mind, remove as may distractions from the space as you can (all of them if possible). Often times I use a sound app such as "Lightning bug" to create a calmer atmosphere.
~ Reading: This can be both good and bad, as I have gotten some books (usually text books) that put me right to sleep, but have also found other books that will keep me awake for hours because I don't want to miss the next part of the adventure.
~ Celestial seasonings "Sleepy time tea": I swear by this tea for 1 main reason, believe it or not... it contains catnip! Keep in mind, catnip has different effects on people like it does cats, for me it is very calming and soothing, for my cat (and my good friend), it wires them like a 6 pack of Redbull.
Hopefully those suggestions help a bit. Let me know what you have already tried, and if any of those methods work out for you.
Good luck, and sleep well!