I marked 6-8 hours, but thinking about it I definitely got less. I tried to fall asleep at 10:45, but two hours later I was still awake. I probably fell asleep at 1, and I woke up at 6:30 (8 AM testing time). I would have liked to sleep longer, but I was actually pretty refreshed and wasn't tired at all during the day. About an hour after I had left the exam (finished ~1 PM) I definitely felt exhausted, though.