Hey Luna. Being a high schooler myself I totally know what you mean. It's like after facing what parts of the day you have to there's no energy or motivation to do anything else. It's kinda embarrassing--most nights I just come home from school, do my homework, eat dinner, Internet, and then be asleep by seven.
So yeah, I can sympathize.
They say things get better though. We just have to choose to believe it.