Homework Makes Me Very Tired

I am a student from Hong Kong. On school day, i go to school for 8 hours, and do homework for 3 hours or even more. After i finished my homework, i have to revise… but i feel very tired. I always fall asleep when i am revising. Then I go bed very late and can't get enough sleep. What i do on the next day is the same, i feel more and more tired each day. I always feel so tired and stressful.