I am a teenager, 17 years old,I am now doing Advanced levels and am constantly tired. Since fifth form(grade 11) I find myself frequently tired and lazy to study. And now that I am in sixth form, the lazinness gets even worse. How can I get rid of this problem?(When I reach home in the evenings, all I want to do is sleep. How can I keep myself up and my brain active to study seriously? I need help!)