Get more
magnesium in your diet. Most North Americans are deficient, and it's a nutrient that helps relax you. Calcium plays a synergistic role with magnesium, but most North Americans consume more than enough of it, and more in a supplemental form might put you out of balance with magnesium.
Avoid caffeine after 4 p.m.
If you're open to herbal aids, try passionflower, whether as a tea or as a capsule. Other options include, chamomile and "sleepytime blends."
Try deep-breathing exercises before bed.
Turn off the electronics. Don't use computers or televisions an hour before you go to bed. Try reading or listening to music (the relaxing kind).