Hi Kristina,
I used go sleepless like you during my days at schools. This was during the exams. Unfortunately I also didn't sleep enough the following days, because of the others exams that followed this. This became a habit or so and I could go sleepless, due to worries not just about studies. I used to stay awake untill 3 or 4 in the morning because my mind would never stop thinking. I used to wonder if I was the only person in the universe facing like this. Sometimes i used to get irritated also. I have this problem for more than 10 years. Also tried to avoid drugs, don't know why? I try to sleep earlier like 8:30 or 9:30PM but can't until 11 or 12 every day. I need atleast 10 hours a sleep, otherwise I am very dull, stressful next day, like you.