So Tired

I am SO tired. Every day about 2pm I get this feeling like there is no way I can make it to the end of the day. I know I only have one class left, but it is a daunting, rowdy 8th period. All I want to do is go home and lay on my couch. Thank God I have a student teacher who is helping me or I don't think I'd make it! Some tell me this will get better once the first trimester is over, others tell me it will only get worse. Please tell me that it will get better, I'm not used to feeling so exhausted.