Oftentimes, adolescents don't know how to label what they're feeling, or they may not even be aware there's been a change in them. Signs and symptoms of anxiety look like: changes in sleep, changes in appetite, moodiness, withdrawing from relationships, changes in personal hygiene, loss of interest in activities, excessive use of technology to escape, anger outbursts, experimenting with drugs or alcohol, statements of hopelessness and despair.