What are some good, effective methods to cure insomnia?

I get frequent bouts of insomnia, as I’m sure we ALL do, but it gets to the point on many nights (and there have been many for me, believe me) where I can’t fall asleep no matter how hard I try and yet I’m so damn tired. I just lay awake feeling restless. Does anybody know of a good way to help combat insomnia? I could really use the added sleep to boost my energy drive at work.