Not surprised by Ichikawa going to sleep at 1am, my brother is 16 and he goes to sleep around 3am EVERY FUCKING DAY. Obviously, no surprise why he wakes up at mid-day hahaha. At his age I'd be sleeping just like Yamada stated, at around 11pm, and if exams were close I'd sleep even earlier to wake up before school and revise the content for the exam.