Always tired,i eat clean,work out 5 days a week and get 8 plus hours of sleep per night. im so exhausted that its hard to function what could b wrong?

See your Doctor: Congratulations, you are already doing the right things! Unless you are over exercising or not resting enough ( which could make you feel exhausted all the time), you should see your Doctor. He can do a complete Hx. and PE and check Laboratory tests to R/O problems commonly found in your age group. Anemia from menstruation, Mononucleosis (kissing disease), or hormonal imbalances like thyroid.