Teen stress is a normal part of teenage life as they participate in school, sports and other extracurricular activities, and engage in various relationships. But pressure to excel or outside influences can cause teenagers to experience too much stress, to the point of an … 3. Behavioral changes. Physical signs of stress in teens include tiredness or fatigue, headaches, constipation, nausea and dizziness, palpitations, and loss of appetite. Some teens may lose or gain weight, while girls may experience a change in their period cycle. Your teen may lose interest in sports and other physical activities as well.