Why have I been so tired all week?

Hello, I'm 14 (nearly 15) and I've been really tired all week. I go to bed at 9:30pm and get up at 7:00am and all week I've just been so tired which hasn't helped me at school in the slightest. Does anyone know why I'm so tired? I'm good at getting up in the morning and usually I don't get this tired. Is it just a faze?