Something could have messed up your sleeping habits in the first place and now your body is adjusting to it, which, at those hours is not good.
Though, being in 8th grade around active puberty time, irregular sleep patterns are very normal. Usually requiring more sleep, for example, 10 hours a night, but not necessarily the times that you sleep. For me personally I would have my normal sleep patterns (12am ~ 8am) and sleep after school for 2 hours (3:30pm~5:30pm)
You can go forward or backwards to fix a sleep schedule. Since you have school during the day, your only option would be to put your sleep schedule forwards (4pm 1st night, 4:30pm the next night) in a gradual fashion.
And speaking of all this, I should probably improve my own sleep habits, lol.