What are the diagnostic changes for Insomnia Disorder across the Diagnostic and Statistical Manual of Mental Disorders (DSM) versions III, III‑TR, IV, 5, and 5‑TR, and the International Classification of Diseases (ICD) versions 10 and 11?

Evolution of Insomnia Disorder Diagnostic Criteria Across DSM and ICD Versions

DSM-III and DSM-III-TR (1980–1994)

The earliest DSM versions classified insomnia primarily by presumed etiology and symptom duration, distinguishing between "primary" and "secondary" insomnia based on whether clinicians believed an underlying medical or psychiatric condition caused the sleep disturbance 1, 2.

• DSM-III and DSM-III-TR categorized insomnia into transient (≤few days), short-term (≤3 weeks), and long-term (>3 weeks) duration categories, though this classification was based on concerns about sedative-hypnotic use rather than empirical evidence of clinical utility 2.
• The primary/secondary distinction assumed that psychiatric or medical disorders caused insomnia, requiring treatment of the underlying condition to resolve sleep problems 2, 3.
• Symptom subtypes (sleep-onset, sleep-maintenance, early-morning awakening) were recognized but not systematically validated as distinct clinical entities 2.

DSM-IV and DSM-IV-TR (1994–2013)

DSM-IV maintained the primary versus secondary insomnia dichotomy but introduced more specific diagnostic categories, with "Insomnia Related to Another Mental Disorder" becoming the most frequent diagnosis (44% of cases) in clinical practice 1.

• The most common DSM-IV diagnoses were "Insomnia Related to Another Mental Disorder" (44%) and "Primary Insomnia" (20.2%), reflecting continued emphasis on presumed causality 1.
• DSM-IV required dissatisfaction with sleep quantity or quality, difficulty initiating or maintaining sleep, and clinically significant distress or impairment, but duration criteria remained variable 4, 1.
• The classification perpetuated the unproven assumption that comorbid conditions caused insomnia rather than coexisting with it 2, 3.

DSM-5 (2013) – Major Paradigm Shift

DSM-5 eliminated the primary/secondary distinction entirely, recognizing insomnia as an independent disorder that can coexist with—rather than be caused by—other medical or psychiatric conditions, fundamentally changing diagnostic and treatment approaches 4, 3.

• Diagnostic criteria now require:

  • Sleep difficulties (initiation, maintenance, or early-morning waking) occurring ≥3 nights per week for ≥3 months 4
  • Adequate opportunity and circumstances for sleep 4
  • Clinically significant distress or daytime impairment 4
  • Symptoms not better explained by another sleep disorder, substance effects, or coexisting medical/mental conditions 4

• The term "Insomnia Disorder" replaced multiple subtypes, consolidating diagnoses into a single category 4, 3.

• DSM-5 recognizes bidirectional, interactive relationships between insomnia and comorbid conditions, requiring treatment of both disorders simultaneously 3.

• The change reflects evidence that insomnia often persists independently even when initially triggered by another condition, and that treating only the comorbid disorder frequently fails to resolve sleep problems 4, 2, 3.

DSM-5-TR (2022)

DSM-5-TR retained the DSM-5 diagnostic framework without substantive changes to insomnia criteria, maintaining the unified "Insomnia Disorder" diagnosis and the ≥3 nights/week for ≥3 months threshold 4.

• The text revision clarified language and updated supporting evidence but did not alter core diagnostic requirements 4.
• Emphasis on dimensional assessment (severity ratings) and developmental considerations was enhanced 4.

ICD-10 (1990–2022)

ICD-10 classified insomnia primarily under "Nonorganic Insomnia" (F51.0) and "Insomnia Due to Emotional Causes," with the latter accounting for 61.9% of diagnoses in clinical practice, reflecting a psychiatric-centric approach 1.

• The most frequent ICD-10 diagnoses were "Insomnia Due to Emotional Causes" (61.9%) and "Insomnia of Organic Origin" (8.9%) 1.
• ICD-10 maintained separation between organic and nonorganic sleep disorders, perpetuating the primary/secondary framework 4, 1.
• Duration criteria were less standardized than in DSM systems, contributing to diagnostic variability 5, 1.

ICD-11 (2022–Present) – Harmonization with DSM-5

ICD-11 fundamentally restructured sleep disorder classification to align with DSM-5, eliminating the organic/nonorganic distinction and recognizing insomnia as a disorder in its own right rather than merely a symptom 4.

• Key structural changes:

  • Sleep-wake disorders were separated into a dedicated chapter (previously embedded within mental/behavioral disorders) 4
  • The childhood/adolescence-specific disorder grouping was eliminated, emphasizing developmental continuity across the lifespan 4
  • Insomnia subtypes were consolidated into "Chronic Insomnia Disorder" with unified diagnostic criteria 4

• ICD-11 adopted the ≥3 nights/week for ≥3 months threshold consistent with DSM-5 and ICSD-3 4.

• The classification emphasizes dimensional approaches (severity ratings) alongside categorical diagnoses to address within-category heterogeneity 4.

• Caregiver input is now emphasized for cognitively impaired and pediatric patients 4.

Critical Diagnostic Pitfalls Across Versions

• Overestimation of prevalence when daytime impairment criteria are inadequately assessed: Studies show DSM-IV-TR and ICSD-3 criteria (which allow more flexible daytime symptom requirements) yield prevalence rates of 23.6% and 20.0% respectively, while DSM-5 and ICD-10 (requiring more stringent daytime dysfunction) yield 8.5% and 9.9% 5.
• Over half of patients classified with insomnia under DSM-IV-TR and ICSD-3 did not report impaired daytime functioning ≥3 days/week, suggesting diagnostic inflation 5.
• Site-related diagnostic variability: Substantial differences in diagnostic patterns across clinical centers reflect inconsistent application of criteria rather than true population differences 1.
• The historical primary/secondary distinction delayed recognition that insomnia requires independent treatment even when comorbid conditions are present 4, 2, 3.

Practical Clinical Implications

The shift from DSM-IV to DSM-5/ICD-11 mandates that clinicians now diagnose and treat insomnia as an independent disorder requiring specific intervention (particularly CBT-I) rather than assuming it will resolve when comorbid conditions are addressed 4, 3.

• Current diagnostic systems (DSM-5, DSM-5-TR, ICD-11, ICSD-3) have converged on similar criteria, reducing diagnostic confusion 4.
• The ≥3 nights/week for ≥3 months threshold is now standard across all major classification systems 4.
• Clinicians must document both insomnia disorder and any comorbid psychiatric/medical conditions as coexisting diagnoses rather than hierarchical relationships 4, 3.
• Polysomnography is not indicated for routine insomnia diagnosis; it is reserved for suspected comorbid sleep disorders (e.g., sleep apnea, periodic limb movements) 4, 6.