Insomnia, from the Latin "in" (not) and "somnus" (sleep), is a condition in which people have a difficulty falling asleep and remaining asleep. It includes a broad spectrum of sleep disorders, from lack of quantity of sleep to lack of quality of sleep. Insomnia is often separated into three types. Transient insomnia occurs when symptoms last from a few days to a few weeks. Acute or short-term insomnia is when symptoms last for several weeks. Chronic insomnia is characterized by insomnia that lasts for months and years.
Insomnia can affect all age groups and is more common in adult women than adult men. The condition can lead to poor performance at work or school, obesity, depression, anxiety, poor immune system function, reduced reaction time, and an increased risk and severity of long-term disease.