waking up too early causes tiredness

I was wondering why I was so lethargic at training on Friday. It was really hard to move and each action felt heavy and half-hearted.
I suspected that it was due to the early morning starts of uni during the week as I slept most of today. I have to find a solution to this problem or it will only become worse throughout the semester. Maybe, I have to go to bed earlier, although this week I went to sleep earlier than usual.