I really found this interesting and I loved it! Did you know that eating a simple delicious cookie can act as an antidepressant? Studies show that snacking on readily digested carbohydrates such as those in a cookie or a bagel can raise the brains level of the chemical serotonin. This is the same target of modern antidepressant medication.
We always thought of chocolate as cheering us up but an Australian scientist concluded recently that eating chocolate to lift your spirit “is more likely to prolong than abort depressed mood.” So therefore its not, as some would claim, an antidepressant.
Try this regime to raise your mood. Include protein in each three of your meals. This will raise blood levels of tryptophan, a chemical that eventually turns into serotonin. The best source of tryptophan comes from seafood. Have a small carbohydrate snack about 3 or 4 hours after each meal and about 1 before your next one. Make sure that your stomach is empty and that you eat no protein between meals. The carbs should be easily digestible such as one or two oatmeal cookies, a third of a bagel, and a slice of whole wheat bread. This will cause the tryptophan in your blood to enter the brain where it is metabolized into serotonin. Elevated serotonin will improve your mood within 20-30 mins. Also following these rules will make you fall asleep quickly at night because at the end of the night, your brain metabolizes serotonin into the natural sleep aid melatonin. From happy to sleepy, all by way of a cookie! :)

I like this theory :) I love cookies. I wonder though, if carbs turn  into serotonin and make you happy, are the people on atkins who are depriving themselves of carbs sadder than those who arent?