If you, like me, spend some nights tossing and turning, you might want to consider your diet as the culprit. Here's how: carbohydrates send tryptophan, an amino acid known to be a sleep aid, to the brain, while protein actually inhibits trytophan's sedative effect. So avoid high-protein dinners and just try to eat a well-balanced meal that contains carbohydrates (don't be afraid to eat carbs). Or you may be mineral deficient; iron, calcium, and magnesium all induce sleepiness. Try taking those supplements in the evening.
Hunger can also keep you awake--maybe you're not eating enough (but don't overdo either; overeating can cause stomach pains that will keep you awake). And finally, maybe you're drinking too much alcohol. A drink can help you go to sleep, but it often causes wakefulness in the middle of the night and can interfere with the body's REM cycle, which is when the most restful sleep occurs.
Ryan, M.J. Instant Health And Happiness. Pg. 53.