The most common anxiety disorder is generalized anxiety disorder (GAD). GAD is characterized by excessive and persistent worry and anxiety about everyday events and activities, such as work, school, health, and relationships. People with GAD often have physical symptoms such as muscle tension, restlessness, fatigue, and difficulty sleeping. GAD affects approximately 6.8 million adults in the United States, and it is more common in women than in men. Other common anxiety disorders include social anxiety disorder, panic disorder, and specific phobias.