Insomnia can be short-lived, lasting only one to two nights. This is called transient insomnia. Transient insomnia is usually due to a new life stressor or a change in our daily routine. Insomnia that lasts more than a few days but less than 1 month is called short-term insomnia. This is usually due to a bigger stressor, such as a short-term illness.
Chronic insomnia can last months or years.
Chronic insomnia is usually due to chronic medical or psychiatric illness or the use of medications. Some studies suggest that one in three Americans suffers from chronic insomnia. Most emotional disorders can cause sleep disturbance. Chronic insomnia can be a symptom of depression, anxiety, dementia, or panic disorder. A number of medical problems can also cause insomnia.