Difficulty falling asleep is called sleep-onset insomnia. Difficulty staying asleep is termed sleep maintenance insomnia. Nonrestorative sleep is the term used to describe sleepiness despite an adequate amount of sleep. 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.