What is the best supplement for someone who is having trouble concentrating while studyng?

A good study setting: Many people have difficulty studying because of sleep problems, trying to study in a bad environment--TV, music on, children playing in the room, other tasks you think you need to do now. Long before you think about supplements, review your study setting and habits. People do not study well for long periods. Schedule breaks to get up and do something else which doesn't involve as much mental focus