Insomnia is sleep disturbance which follows one of two main patterns. The first is difficulty falling asleep, and the second is difficulty staying asleep. While virtually everyone experiences trouble sleeping from time to time, the condition is considered medical and in need of treatment when insomnia becomes chronic. Causes range from disruptions in the circadian rhythms which regulate sleep-waking cycles to substance abuse and anxiety disorders, but insomnia can also be a symptom of a more serious underlying illness. Treatment can include prescription medications designed to induce sleep, therapeutic approaches which promote healthier sleeping habits, or a combination of both.