Insomnia

Insomnia is difficulty falling asleep or staying asleep or a disturbance in sleep that makes sleep seem inadequate or unrefreshing. Symptoms include irritability, fatigue during the day, and problems concentrating or performing under stress.

To diagnose insomnia, doctors evaluate a person's sleep pattern, use of drugs (including alcohol and illicit drugs), degree of psychologic stress, medical history, and level of physical activity. Some people need less sleep than others, so the diagnosis of insomnia is based on a person's individual needs.