Hi there, thanks for asking. Many adolescents find delayed sleep phase syndrome
. It becomes very hard to sleep until several hours after midnight, because melatonin
secretion begins with delay in some adolescence. There is a test named DLMO which can measure melatonin secretion. It could also be related to working with computer or watching TV in the late night. Even if you have to work on some nights on your homework, they are some yellow glasses which filter the blue part of the light and make sleeping following work with computer easier. However, it is better to work with computer just until early evening. I wish you the best health.