Suggest Treatment For Chronic Severe Fatigue

I have suffered from severe fatigue for years and it is getting worse. I have had phsicals/blood work and all has came back fine. I have sought psychiatry. I am currently on lamictal 200mg for bi-polar and prosac 40mg for depression. I can only stay up for about 4hours and then I am ready for a 3 hr nap. I get atleast 8 hrs sleep a night. Any suggestions?