Sleep Disorders

Updated 24 August 2018

What is insomnia?

Insomnia refers to the inability to fall sleep or to maintain sleep, or waking up early and not getting enough sleep.

While occasional insomnia as a symptom is very common, “insomnia disorder” is a medically classifiable condition in which the above symptoms are associated with impaired functioning during the day.

The insomnia should also last for more than a month for the “insomnia disorder” diagnosis to apply. 

Insomnia is the most common sleep disorder.

The International Classification of Sleep Disorders (ICSD-3) defines insomnia disorder as follows: “Insomnia is a persistent difficulty with sleep initiation, duration, consolidation, or quality that occurs despite adequate opportunity and circumstances for sleep, and results in some form of daytime impairment.

When no underlying cause can be found, a person is said to be suffering from primary insomnia. Where a cause is found (for example, a medical condition), it’s classified as secondary insomnia.”

Insomniacs may experience loss of energy and enthusiasm, have problems with memory and concentration, and may feel ill, sleepy and frustrated.

Poor sleep can be associated with accidents and lower work productivity, and may worsen medical and psychological conditions. These consequences make insomnia an important health problem that deserves serious attention.

Course and prognosis of insomnia

Insomnia may arise suddenly (acute) or gradually (chronic). In acute insomnia, there’s usually a triggering factor that can be identified – for example separation, bereavement, change in sleep schedule, or an increase in daily stress levels. 

By definition, acute insomnia is short-lived and can usually be easily managed by a short course of sleeping tablets and counselling addressing the triggering factors. Chronic insomnia has a more insidious onset over a period of time and its course can be situational, recurrent or persistent. 

The earlier you seek help for insomnia, the better the clinical outcome. 

Read more:
Who gets insomnia?

Reviewed by Dr Irshaad Ebrahim, specialist neuropsychiatrist in sleep disorders at The London Sleep Centre and The Constantia Sleep Centre. FRCPsych. April 2018.


Ask the Expert

Sleep disorders expert

Dr Alison Bentley is a general practitioner who has consulted in sleep medicine and sleep disorders, in both adults and children of all ages, for almost 30 years. She also researches and publishes on a number of sleep-related topics both in formal research journals and lay publications including as editor of Sleep Matters, an educational newsletter on sleep disorders for doctors.

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