Insomnia is a sleep disorder characterized by difficulty falling asleep, staying asleep, or waking up too early. It can be acute (short term) or chronic. Insomnia can be caused by stress, anxiety, medications, substances, or other mental disorders. Symptoms include trouble falling asleep, waking frequently during the night, and feeling unrefreshed upon waking. Treatments include behavioral therapies, relaxation techniques, avoiding stimulants before bed, and medications called hypnotics. Past studies have found links between insomnia and depression as well as suicidal behavior.