I know that lack of sleep isn't exactly a good thing, and can lead to things like dizziness and lack of energy. I'm also pretty sure that a healthy amount of sleep for the character in question (who is 11) would be somewhere around nine to ten hours a day. At this point in the story, the character is getting three or four hours at the most, and barely manages keeps himself awake for the rest of the day.
My question is: how long can a person continue in a similar state before he or she starts to feel the more serious symptoms? As in hallucinations, fainting and so on.
If it's any help, the character is a relatively normal Japanese schoolkid living in Tokyo, and not likely to take pills or drink that much coffee.
Thanks in advance!