Weird sleeping problem

[Froge]

During weekdays, I wake up for classes at 9:30 on mondays / wednesdays / fridays and at 10:30 for class on tuesdays / thursdays. However, I always sleep the same amount of time the night before (at 1:00 am) so for 9:30 classes I pretty much have 1 less hour of sleep. Despite this, I almost always feel more tired when I wake up at 10:30 where I've had one more hour of sleep.

On weekends I wake up at 11:30 and I don't feel tired at all. I do feel a bit tired when I wake up at 9:30, but it's not as brain crushing as when I wake up at 10:30. So basically I have this weird interval where I always feel tired if I wake up at that time.

What say ye powers of forum diagnosis?