Stress is the combination of psychological, physiological and behavioral responses to perceived threats or challenges in the environment. There are three levels of stress: low stress which can lead to boredom or frustration, optimal stress which provides energy for tasks, and high stress which is distressing and can negatively impact health. The body's response to stress follows a three stage process of alarm, resistance and exhaustion. Sources of stress include daily hassles, major life events and catastrophes. Stress responses include psychological, physiological and behavioral reactions in the body and mind. Chronic stress can lead to burnout which involves worsening psychological, physical and behavioral dysfunction over time if not managed effectively.