I did research in a sleep lab for a year. There's a lot of comments on here about various drugs, so I won't repeat that, but I think there are some behavioral practices worth mentioning.
1. The bed is where you sleep. Period. Not where you read, not where you watch TV, not where you play with your dog, not where you talk to your wife. It's where you sleep. Or participate in pre-sleep activities
2. If you cannot sleep, do not stay in bed. This goes against Rule #1. Get up and do something that will allow you to become sleepy (for me, it's reading). Do not subject yourself to anything that is over-stimulating - no TV, no movies, no video games, no computers. Reading works for many people, so long as you aren't reading something you're so captivated by that you'd actually put off sleep to read it. Do not make yourself comfortable doing this. Do not lounge in the overstuffed leather recliner. Sit on a kitchen chair or otherwise uncomfortable spot. After about 15 or 20 minutes, reassess how you feel. Close your eyes. If you feel tired, go back to bed.
3. While in bed, DO NOT LOOK AT THE ALARM CLOCK. It will make you anxious and this is counter-productive.
4. Develop a nighttime routine. This should not include anything that stimulates you. If you shower at night, do it at least an hour before bedtime. The hour before bed should be peaceful and stress-free. Try aromatherapy.
5. Make your surroundings conducive to sleep. Many people don't realize the effects of their environment on anxiety levels. Your bedroom should be a place that feels calm and peaceful. Look at your wall color for 15 seconds. How does it make you feel? Look at your room as a whole. Is it messy? This can make many people feel anxious on a subconscious level.
That's all I can think of for now. I've overcome my insomnia with a combination of these tactics and those mentioned above. I shower an hour before bed, put on my PJs and brush my teeth, then read in a quiet room for a bit before bed.
Sometimes I take a melatonin tablet, and sometimes I have a glass of red wine while reading. For me, it's really key to maintain constant sleep and wake times. I realize that's not possible for everyone, for it's very good to do when you can.