How to beat feeling sleepy in the office?

Hi, I am a 24yr. old high tech professional and my job entails me to spend around 10 hours each day infront of the comp ( has a LCD screen) and when I go home I work as a freelancer ..which makes it another 4-5 hrs infront of the comp ( my laptop). I hardly get o watch TV. I sleep for around 5-6 hrs a day and when I come to office in the morning.. I still feel that I could do with some sleep. Do you guys have any inputs who I can beat this???