Clinical review: Insomnia

The criteria for diagnosis of insomnia and how to help patients to manage the factors that cause it, including differential diagnoses, use of daily sleep diaries and the role of cognitive therapy, hypnotic drugs and melatonin.

Section 1: Epidemiology and aetiology
Section 2: Making the diagnosis
Section 3: Managing the condition
Section 4: Prognosis
Section 5: Case study
Section 6: Evidence base

Section 1: Epidemiology and aetiology

The International Classification of Sleep Disorders, third edition (ICSD-3) defines six major categories of sleep dysfunction,1 of which insomnia disorder is the most prevalent. The general definition of insomnia is characterised by ‘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’.2 More specifically, the ICSD-3 also divides insomnia into six subtypes:

(1) chronic insomnia disorder
(2) short-term insomnia disorder
(3) other insomnia disorder
(4) isolated symptoms and normal variants
(5) excessive time in bed
(6) short sleeper

The estimated prevalence of insomnia disorder, accompanied by daytime consequences, is 8-12% for the adult population. An estimated 30-50% of the population will experience insomnia symptoms. In the UK, the prevalence of insomnia is showing a modest increase.3 Age-specific rates show a steady rise in prevalence across the lifespan and, at all ages, women generally report higher rates of insomnia than men.4

Insomnia risk is elevated among individuals with long-term health conditions, such as myocardial infarction, stroke, hypertension, diabetes, chronic pain, depression and anxiety.5 In addition, chronic insomnia is associated with elevated accident risk, delayed recovery from acute illness, and increased use of healthcare services.4

Aetiology of insomnia

Chronic insomnia is thought to result from the interaction of three factors:6

  • Predisposing factors – a physiological or psychological vulnerability such as a genetic predisposition, a predisposition to anxiety, susceptibility to cognitive intrusions, and attentional bias.
  • Precipitating factors - acute, momentary, physical, psychological or situational events that disturb sleep.
  • Perpetuating factors - maladaptive behavioural responses to sleep disturbance which, over time, maintain insomnia as a chronic problem.

Using this model we can explain why some precipitating events (acute pain, childbirth, bereavement) can disturb sleep in a substantial proportion of the population, but produce chronic insomnia in only a minority (the predisposed). It also recognises that perpetuating factors (degraded sleep schedules, learned arousal, loss of sleep habit) can maintain insomnia symptoms long after precipitating factors have resolved.

Section 2: Making the diagnosis

Criteria for diagnosis

Using the ICSD-3 criteria as a guide, insomnia can be diagnosed where the patient reports difficulty getting to sleep or staying asleep resulting in impairment to daytime functioning. These symptoms have to occur three or more times a week and persist for at least a month. Daytime symptoms typically include mood disturbances and impaired concentration, and most patients with insomnia report daytime fatigue, while fewer report daytime sleepiness. The Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-V)7 reports similar requirements for a diagnosis as the ICSD-3. Previous distinctions between primary and secondary insomnia have been removed from diagnostic manuals, but insomnia can be comorbid with a range of disorders.

Determining insomnia disorder

Insomnia is a disorder that is diagnosed based on subjective reporting of symptoms as defined by the ICSD-3 or DSM-5. The gold standard for diagnosing insomnia is the clinical interview. Ask about the frequency and severity of sleep problems and daytime impact. Additionally, a sleep history - including typical sleep and wakefulness patterns, typical sleep quality, levels of alcohol and caffeine consumption, and daytime napping behaviour - can provide important background information. Standardised screening instruments, such as the Insomnia Severity Index8 and Sleep Condition Indicator9 can be used to get an initial overview of insomnia complaints.

The use of a simple sleep diary, such as the consensus sleep diary,10 where patients record bedtimes, waking times, hours slept and sleep quality each morning for at least a week, is recommended. Completing a daily diary gives an insight into the patient's sleeping habits and, if continued during therapy, the treatment outcome.

The use of polysomnography to diagnose insomnia is not recommended, though in some cases actigraphy has been used as a supportive measure.

Differential diagnoses

Referral to a specialist sleep service should only be considered in cases where differential diagnosis is complicated by signs and symptoms of other sleep disorders, particularly obstructive sleep apnoea (OSA) or restless legs syndrome (RLS). These, and other, sleep disorders are not categorised as insomnia disorder, but they are often accompanied by symptoms of insomnia.

  • OSA includes breathing pauses during sleep and excessive daytime sleepiness. A comprehensive sleep history can give insights into these complaints. Diagnoses need to be confirmed by polygraphy or polysomnography.11
  • RLS can be identified based on four criteria proposed by the International RLS Study Group as follows: an urge to move the legs accompanied by unpleasant sensations, which is present at rest, which is relieved by movement and peaks at night or in the evening. The criteria can be assessed by the Restless Legs Syndrome Rating Scale.12
  • Circadian rhythm sleep disorder is another common sleep disorder. This is characterised by a disrupted internal sleep-wake clock, resulting in disturbed sleep and daytime fatigue. The rhythm can be delayed, advanced or irregular.13

Section 3: Managing the condition

Insomnia can be treated with psychological and pharmacological approaches. NICE guidelines recommend cognitive behavioural therapy (CBT) for treating insomnia.

Cognitive behavioural therapy

CBT for insomnia has five main components:

  • Sleep hygiene – general guidelines about healthy sleep behaviours and a healthy sleep environment
  • Sleep restriction – limiting the opportunity to sleep to increase more consolidated and efficient sleep
  • Stimulus control – reducing time spent in bed awake to reassociate the bed/bedroom with sleep
  • Cognitive therapy – targeting and changing beliefs and attitudes around sleep and insomnia
  • Relaxation – reducing somatic tension or intrusive methods by relaxation techniques

CBT for insomnia can be effectively delivered as a face-to-face treatment, group therapy, digital therapy and self-help.

Hypnotic drugs

Hypnotic drugs have proved effective in the management of short-term sleep disturbances (up to three to four weeks), provided they are prescribed within their licence and an exit strategy is agreed with the patient.

In practice, sleep medication is often used longer than the maximum duration of three to four weeks. However, long-term use can introduce major problems including tolerance, dependence, residual sedation and increased accident risk. In long-term use, the benefits of hypnotics may be outweighed by the risk of harm.


The hormone melatonin has an important role in entraining the circadian rhythm and can shift the timing of sleep/wake cycles. Where sleep difficulties are caused by circadian desynchronisation (for example, jet lag, or where sleep cycles are only weakly entrained to the 24-hour clock), melatonin may help. Melatonin is more likely to be beneficial for circadian sleep disorders than insomnia.

Section 4: Prognosis

A study of 388 adults with untreated insomnia found that 74% still reported insomnia after one year and 46% after three years.14 More severe symptoms are associated with lower remission levels and insomnia tends to be most persistent in women and older age groups. However, sustained improvements are seen in 70-80% of patients treated with CBT.

Section 5: Case study

Case description

A married, retired 63-year-old man with a history of chronic insomnia and intermittent hypnotic drug use presented with recent sleep disturbances. He had not taken hypnotics for over six months but now reported long sleep latencies (up to two hours), unrefreshing sleep and daytime fatigue, and reluctantly requested sleeping tablets.

Although mildly hypertensive (for which he was prescribed beta-blockers), the patient was otherwise healthy. He was referred to a psychological wellbeing practitioner. The patient had a sleep and mental health assessment, including a sleep diary. He was not depressed but had serious problems with sleep hygiene, sleep schedules and stimulus control (time spent in bed but awake). He spent his day gardening then, after an early evening shower, not wanting to dress in clean clothes 'just for a couple of hours', he put on pyjamas, retiring to bed at about 10pm. Knowing he would not fall asleep, he would take a newspaper or magazine to read; his wife joined him at about 11pm. But after settling down, he was restless and rarely fell asleep before 1am. However, on waking early (typically around 6am), he felt obliged to get up.


The patient was treated according CBT principles which targeted three areas:

  • differentiating daytime from bedtime (wear pyjamas only for bed)
  • reducing time spent in bed awake (go to bed only when sleepy, but not before the agreed time)
  • reassociating bed with sleep (don't read in bed, get up if you can't sleep, avoid daytime naps).

A sleep window was agreed, defined by an earliest bedtime and a latest getting up time, to accommodate only the average duration of sleep reported in the sleep diary to consolidate his sleep.

Sleep latency and quality improved steadily over six weeks without the use of any hypnotics. Improvements were maintained at three and six-month follow-ups.

Section 6: Evidence base

Clinical trials

Many clinical trials have been supportive of the effectiveness of CBT as a treatment for insomnia. Suggested reviews on the topic are:


  • NHS Clinical Knowledge Summaries (CKS). Guidance on the management of insomnia, April 2015. Available from: (accessed 18 May 2017)
  • NICE. Guidance on the use of zaleplon, zolpidem and zopiclone for the short-term management of insomnia. TA77. London, NICE, April 2004. Available from: (accessed 18 May 2017)

Further Reading

Online ( offers information and advice on self-help. Digital solutions to CBT for insomnia have been shown to be effective and are increasingly available.15

  • Professor Kevin Morgan is professor of psychology, Loughborough University
  • This is an updated version of an article that was first published in January 2013. This article was updated by Dr Annemarie Luik and Dr Rachel Sharman, post-doctoral researchers, Sleep & Circadian Neuroscience Institute, University of Oxford and Professor Colin Espie, professor of sleep medicine, Somerville College, University of Oxford

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  1. American Academy of Sleep Medicine. The International Classification of Sleep Disorders – Third Edition (ICSD-3). Westchester, American Academy of Sleep Medicine, 2014.
  2. Zucconi, M and Ferri R. Classification of sleep disorders. In: Basetti C, Dogas Z, Peigneux P (eds). ESRS Sleep Medicine Textbook. Regensburg (2014): European Sleep Research Society.
  3. Calem M, Bisla J, Begum A et al. Increased prevalence of insomnia and changes in hypnotics use in England over 15 years: analysis of the 1993, 2000, and 2007 national psychiatric morbidity surveys. Sleep 2012, 35:377-84
  4. Morgan K. The epidemiology of sleep. In: Morin CM, Espie CA (eds). The Oxford Handbook of Sleep and Sleep Disorders. New York, OUP, 2012.
  5. Kalmbach DA, Pillai V, Arnedt JT et al. DSM-5 insomnia and short sleep: comorbidity landscape and racial disparities. Sleep 2016, 39:2101-11.
  6. Spielman AJ, Caruso LS, Glovinsky PB. A behavioral perspective on insomnia treatment. Psychiatric Clinics of North America 1987,10:541-53
  7. American Psychiatric Association. Diagnostic and statistical manual of mental disorders (5th ed.). Washington, American Psychiatric Association, 2013.
  8. Bastien CH, Vallières A, Morin CM. Validation of the Insomnia Severity Index as an outcome measure for insomnia research. Sleep Medicine 2001, 2:297-307.
  9. Espie CA, Kyle SD, Hames P et al. The Sleep Condition Indicator: a clinical screening tool to evaluate insomnia disorder. BMJ Open 2014, 4:e004183.
  10. Carney CE, Buysse DJ, Ancoli-Israel S et al. The consensus sleep diary: standardizing prospective sleep self-monitoring. Sleep 2012, 35:287-302.
  11. Epstein LJ, Kristo D, Strollo PJ Jr et al; Adult obstructive sleep apnea task force of the American Academy of Sleep Medicine. Clinical guideline for the evaluation, management and long-term care of obstructive sleep apnea in adults. J Clin Sleep Med 2009, 5:263-76.
  12. The International Restless Legs Syndrome Study Group. Validation of the International Restless Legs Syndrome Study Group Rating Scale for restless legs syndrome. Sleep Med 2003, 4:121-32
  13. Sack RL, Auckley D, Auger RR et al; American Academy of Sleep Medicine. Circadian rhythm sleep disorders: part I, basic principles, shift work and jet lag disorders. An American Academy of Sleep Medicine review. Sleep 2007, 30:1460-83
  14. Morin CM, Bélanger L, LeBlanc M et al. The natural history of insomnia: a population-based 3-year longitudinal study. Arch Intern Med 2009, 169:447-53
  15. Seyffert M, Lagisetty P, Landgraf J et al. Internet-Delivered Cognitive Behavioral Therapy to Treat Insomnia: A Systematic Review and Meta-Analysis. PLoS One 2016, 11:e0149139.

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