Approximately 60 to 70 million adults in the United States alone are affected by insomnia. Daytime symptoms of insomnia include tiredness, lack of energy, difficulty concentrating, and irritability. Recent epidemiologic research focusing on the quality of life has identified significant insomnia-related morbidities that relate to work productivity, health care utilization, and risk of depression. Insomnia is associated with diminished work output, absenteeism, and greater rates of accidents.