ICD-117A00	CHRONIC INSOMNIA Chronic insomnia
ICD-10F51.0	Nonorganic insomnia
DSM-5-TRF51.01	Insomnia Disorder

1. Definition and nosology

Insomnia (ICD-11: 7A00; DSM-5-TR: F51.01 Insomnia Disorder) — difficulty initiating sleep, maintaining sleep, and/or early morning awakening; daytime functional impairment. Duration ≥ 3 months, frequency ≥ 3 times per week.

2. History

• DSM-IV — ‘Primary Insomnia’; DSM-5 (2013) — ‘Insomnia Disorder’ — primary/secondary distinction abolished.
• AASM (American Academy of Sleep Medicine) — Clinical Practice Guidelines (2021 CBT-I, 2017 pharmacological).
• European Insomnia Guideline (Riemann D. 2023).
• NICE TA922 (2023).

3. Epidemiology

• Lifetime prevalence: chronic insomnia 10–15%; insomnia symptoms 30–35%.
• Sex: 1.5 times higher in females.
• Increases with age.
• Comorbidity: MDD ~50%, anxiety, pain, COPD, circadian disorders.

4. Aetiology and pathogenesis

• Spielman 3P Model — Predisposing, Precipitating, Perpetuating.
• Hyperarousal hypothesis — physiological and cognitive stimulation.
• Behavioral factors — irregular schedule, caffeine, alcohol, screen use, non-sleep activities in the bedroom.

5. Clinical features

• Sleep difficulty (falling asleep), maintenance, early awakening.
• Daytime symptoms: fatigue, irritability, concentration difficulties, occupational/academic impairment, somatic (headache, GI).
• Impact on performance, risk of accident.

6. Diagnosis

6.1 Unified diagnostic criteria

A. Sleep difficulty (onset, maintenance, or early awakening).

B. Despite adequate sleep opportunities.

C. Daytime functional impairment.

D. Duration ≥ 3 months, ≥ 3 times per week.

E. Not fully explained by another sleep disorder, substance, or medical condition.

6.2 Source-specific clarifications

• AASM — CBT-I first-line.
• NICE TA922 (2023) — daridorexant only if CBT-I has been tried and did not work, or is unavailable; that is, CBT-I comes first.

6.3 Diagnostic algorithm

1. Clinical interview + sleep diary for 1–2 weeks.
2. ISI (Insomnia Severity Index), PSQI.
3. Differential — obstructive sleep apnea (STOP-BANG), restless legs, circadian.
4. Comorbidity (MDD, anxiety).
5. Polysomnography only in atypical cases or suspicion of another sleep disorder.

6.4 Differential diagnosis

7. Examination and assessment

• ISI, PSQI.
• Sleep diary.
• STOP-BANG (OSA), Epworth Sleepiness Scale.
• TSH, ferritin.

8. Treatment

8.1 General principles (AASM 2021 · European Insomnia Guideline 2023 · NICE TA922 2023)

1. CBT-I (cognitive behavioural therapy for insomnia) — first line; the gold standard in chronic insomnia; superior long-term efficacy to pharmacotherapy (Mitchell M.D. BMC Fam Pract 2012 meta-analysis). 5 main components:
   • Stimulus control (Bootzin) — bed only for sleep;
   • Sleep restriction (Spielman) — restricting time in bed to equal sleep time;
   • Cognitive therapy — catastrophic thoughts about sleep;
   • Sleep hygiene;
   • Relaxation training.
2. Digital CBT-I (Sleepio, SHUTi) — NICE HTG624 (2022): a cost-saving option in primary care for people who would otherwise be offered sleep hygiene or sleeping pills; direct comparison with face-to-face CBT-I is not established.
3. Pharmacotherapy — short-term (2–4 weeks), when there is no response to CBT-I or it is unavailable:
   • Z-drugs (zolpidem, zopiclone, eszopiclone);
   • Benzodiazepine (temazepam) — tolerance, dependence risk;
   • Newer — suvorexant, lemborexant (orexin antagonists) — less dependence;
   • Doxepin at low dose (3–6 mg);
   • Melatonin — for circadian component or in elderly; ramelteon (melatonin agonist).
4. In older adults — Beers Criteria; avoid benzodiazepines and antihistamines (diphenhydramine).
5. Comorbid depression — sedative antidepressant (mirtazapine, trazodone) — long-term use side effects should be considered.

8.2 Source-specific clarifications

• AASM Clinical Practice Guideline for Behavioral and Psychological Treatments (Edinger J.D. 2021).
• European Insomnia Guideline (Riemann D. J Sleep Res 2023).
• NICE TA922 (2023) — CBT-I must be tried before moving to medication.

Treatment methods

1. CBT for insomnia (CBT-I — Cognitive Behavioral Therapy for Insomnia), 5 components — Stimulus control, sleep restriction, cognitive therapy, sleep hygiene, relaxation.
2. Digital CBT-I (Digital) — Sleepio, SHUTi — internet-based.
3. Orexin Antagonists — Suvorexant, lemborexant — lower addiction potential.
4. Insomnia Severity Index (ISI — Insomnia Severity Index) — 7-item screening.
5. Sleep Diary — 1–2 weeks baseline indicators.

9. Prognosis

• Response to CBT-I 70–80%, remission ~40%; the effect is sustained long-term.
• Without treatment, chronic course and comorbidity (MDD, anxiety).

10. Myths and misconceptions

Myth 1: “Sleep medications are the main treatment for insomnia”

Evidence: AASM 2021 — CBT-I first-line; pharmacotherapy short-term adjunct; long-term use tolerance, dependence.

Myth 2: “Alcohol helps with sleep”

Evidence: Alcohol reduces REM, causes midnight awakenings, leads to chronic insomnia.

Myth 3: “Antihistamine (diphenhydramine) is safe in the elderly”

Evidence: Beers Criteria — antihistamines in the elderly: anticholinergic side effects (falls, cognitive decline); avoid.

Myth 4: “Valerian, kava are safe alternatives for insomnia”

Evidence: valerian — Leach M.J., Page A.T. Sleep Med Rev 2015;24:1–12 — evidence for effect insufficient; kava hepatotoxicity.

Myth 5: “8 hours of sleep is necessary for everyone”

Evidence: Individual need 6–9 hours; important is daytime function.

Myth 6: “Waking up during the night is harmful”

Evidence: Brief awakenings are normal; stimulus control — rise if you can't sleep for 20 min.

11. Sources

1. WHO. ICD-11. 7A00 Insomnia disorders. 2024.
2. APA. DSM-5-TR. 2022.
3. Edinger J.D. et al. Behavioral and psychological treatments for chronic insomnia disorder in adults: an AASM clinical practice guideline. J Clin Sleep Med 2021;17(2):255–262.
4. Riemann D. et al. The European Insomnia Guideline 2023. J Sleep Res 2023;32(6):e14035.
5. Mitchell M.D. et al. Comparative effectiveness of cognitive behavioral therapy for insomnia: a systematic review. BMC Fam Pract 2012;13:40.
6. Buysse D.J. et al. Efficacy of brief behavioral treatment for chronic insomnia in older adults. Arch Intern Med 2011;171(10):887–895.
7. National Institute for Health and Care Excellence. Sleepio to treat insomnia and insomnia symptoms. HealthTech guidance HTG624. London: NICE; 2022.
8. National Institute for Health and Care Excellence. Daridorexant for treating long-term insomnia. Technology appraisal guidance TA922. London: NICE; 18 October 2023.