Losing focus

So today was my personal best on time spendt at school this semester so far: 10 hours. Sadly I wasn't that effective though. I met with my group as usual and we worked on the presentation for IM round 4. We found a lot of things we felt as if we had to look into all over again though and it will take some time to finish it all, really demotivating. We agreed on who will be saying what and stuff as well, so thats good at least. Im just sick and tired of having to stay at school for hours and hours studying all the time, have to remain focused but it was really quite hard today. Wasn't all bad though....School was apparently celebrating 5000 likes on facebook, so they gave out cupcakes to everyone - they were really good too, hehe.
Now Im really tired and Im considering to just.. go to sleep really, at 21.30 thats just sad.