This site is intended for healthcare professionals

Go to /sign-in page

You can view 5 more pages before signing in


Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

Insomnia can be described as difficulty falling asleep at bedtime, waking up during the night several times or for a long time, and/or waking too early with inability to return to sleep.

  • several organisations with interest in sleep disorders have put forward varying definitions of insomnia. All of these definitions share several key elements:
    • unsatisfactory sleep, either in terms of sleep onset, sleep maintenance or early waking
    • impaired daytime well-being and subjective abilities and functioning (1,2)

Insomnia can be classified in several different ways.

  • it can be categorized as
    • primary - without a co-morbid condition
    • secondary - associated with physical or psychiatric co-morbidities, drugs or substance abuse (2)
  • it can also be divided according to the duration
    • chronic
      • presence of symptoms for at least three days a week (not necessarily every night) for at least three months
      • pre-sleep arousal (feeling sleepy before bed but then becoming more alert and the unable to sleep once in bed) is common (3)
    • acute
      • symptoms present for less than three months’ duration
      • most people will experience it at some point in any given year
      • usually caused by stress or change in the sleep pattern e.g. - with travel, busy periods at work, illness, or emotional upset
      • once the trigger is removed sleep usually returns to normal (3)

Insomnia (difficulty in either sleep initiation or maintenance at least once a week) affects around one third of adults in the Western countries. It affects 10-20% of the general population depending upon the defining criteria adopted.

  • a higher incidence is seen in women and with increasing age
    • people over 65 show more sleep maintenance problems but a decrease in reported daytime problems compared with younger age groups (1)
  • prevalence is between 1.5–2 times higher in women than in men (1)
  • insomnia is a long-term disorder; many people have had insomnia for more than two years (1)
  • approximately half of all diagnosed insomnia is comorbid with a psychiatric disorder (1)

Primary insomnia is a diagnosis of exclusion, and accounts for around 15% of chronic insomnia

There is at least a two-fold increased risk of subsequent depression and anxiety disorder in patients with pre-existing insomnia (1)

  • insomnia has been associated with:
    • (a) an increased risk of developing subsequent depression;
    • (b) an increased duration of established depression; and
    • (c) relapse following treatment for depression

  • poor sleep quality also seems to correlate with high negative and low positive emotions, both in clinical and subclinical samples. Good sleep seems to be associated with high positive emotions, though not necessarily with low negative emotions

Insomnia is now recognised as reliably associated with mental health disorders including risk of depression and suicide, cardiovascular disease and type 2 diabetes (1)

  • increased fatigue, impaired work productivity, reduced quality of life, and relationship dissatisfaction are also common in those with insomnia
    • such impaired functioning is an important driverfor help-seeking behaviour (1)


Related pages

Create an account to add page annotations

Annotations allow you to add information to this page that would be handy to have on hand during a consultation. E.g. a website or number. This information will always show when you visit this page.