I think it is not suitable for high school students to study till late at night.The first reason is because teenagers are supposed to be sleeping for at least 8 hours a day.Secondly,if they do not have enough rest,it would be harder for them to pay attention in class; it would be a really bad idea to do that as you will need to do a lot more revision yourself if you didn’t listen what the teacher told you during lesson.Lastly,it would affect their health if they didn’t have enough sleep,they are more likely to catch a disease as their body could afford enough energy to protect himself.