These are some natural things that I've tried in the past that have helped me.
L-triptophan, SAM-E, exercise!
there is also st. john's wort but i have not tried it.
overall i would recommend SAM-E in terms of supplements. look into it. it helps you to create more serotonin. can be found at drug stores by the supplements usually and is fairly cheap, give it a try
hope this helps someone...anyone