I Always Get Tired Around The Time I Get Back

I always get tired around the time I get back from school(i'm in high school) and a lot of times I will get these headaches where my head just feels super fragile. I don't like any loud or sharp noises or any lights when this happens so I pretty much fall asleep bc of how tired it makes me and take an ibuprofen. I drink a normal and consistent amount of water through the day, my sleep schedule is not as regular, but I even get this on days where I had a full night's rest. Also sometimes when I try to go to sleep at night I cant fall asleep but this only goes on for about 2-3 hours max. I'm not even thinking about anything when this happens, I'm just blank minded or thinking about trying to get comfortable enough to go to sleep. I'm not depressed or anything, I'm generally a happy person, but I am very curious as to what is causing this; it may end up being a very simple answer. Thanks, whoever answers.