Insomnia, or sleeplessness, is a sleep disorder in which there is an inability to fall asleep or to stay asleep as long as desired. While the term is sometimes used to describe a disorder demonstrated by polysomnographic evidence of disturbed sleep, insomnia is often practically defined as a positive response to either of two questions: "Do you experience difficulty sleeping?" or "Do you have difficulty falling or staying asleep?"
Thus, insomnia is most often thought of as both a sign and a symptom that can accompany several sleep, medical, and psychiatric disorders characterized by a persistent difficulty falling asleep and/or staying asleep or sleep of poor quality. Insomnia is typically followed by functional impairment while awake. Insomnia can occur at any age, but it is particularly common in the elderly. Insomnia can be short term (up to three weeks) or long term (above 3-4 weeks), which can lead to memory problems, depression, irritability and an increased risk of heart disease and automobile related accidents.
Insomnia can be grouped into primary and secondary, or comorbid, insomnia. Primary insomnia is a sleep disorder not attributable to a medical, psychiatric, or environmental cause. It is described as a complaint of prolonged sleep onset latency, disturbance of sleep maintenance, or the experience of non-refreshing sleep. A complete diagnosis will differentiate between:
- insomnia as secondary to another condition,
- primary insomnia co-morbid with one or more conditions, or
- free-standing primary insomnia.
Read more about Insomnia: Risk Factors For Insomnia, Symptoms and Comorbidities, Diagnosis, Treatment, Epidemiology