Insomnia is a sleep disorder characterized by difficulty falling or staying asleep. There are different types of insomnia including acute, chronic, comorbid, onset, and maintenance insomnia. Insomnia can be caused by stress, poor sleep habits, lifestyle factors, mental health conditions, physical health conditions, and certain medications. Effects of insomnia include lower performance, higher risk of accidents, psychiatric problems, health issues, and substance abuse. Treatment may include improving sleep habits and lifestyle changes for mild insomnia or prescription sleeping pills for more severe insomnia.