Insomnia is a sleep disorder that is characterized by difficulty falling and/or staying asleep. People with insomnia have one or more of the following symptoms:
-- Difficulty falling asleep
-- Waking up often during the night and having trouble going back to sleep
-- Waking up too early in the morning
-- Feeling tired upon waking

Types of Insomnia
There are two types of insomnia: primary insomnia and secondary insomnia.

Primary insomnia:
Primary insomnia means that a person is having sleep problems that are not directly associated with any other health condition or problem.
Secondary insomnia: Secondary insomnia means that a person is having sleep problems because of something else, such as a health condition (like Asthma, depression, arthritis, cancer, or heartburn); pain; medication they are taking; or a substance they are using (like alcohol).

Acute vs. Chronic Insomnia
Insomnia also varies in how long it lasts and how often it occurs. It can be short-term (acute insomnia) or can last a long time (chronic insomnia). It can also come and go, with periods of time when a person has no sleep problems. Acute insomnia can last from one night to a few weeks. Insomnia is called chronic when a person has insomnia at least three nights a week for a month or longer.