What are the changes in the diagnostic criteria for hypersomnolence disorder across the Diagnostic and Statistical Manual of Mental Disorders (DSM) versions III, III‑TR (Text Revision), IV, V, and V‑TR (Text Revision), and the International Classification of Diseases (ICD) versions X and XI?

Evolution of Hypersomnolence Disorder Diagnostic Criteria

The diagnostic criteria for hypersomnolence disorder have undergone substantial evolution across DSM and ICD versions, with the most significant changes occurring between DSM-IV and DSM-5, where the disorder was formally renamed and reconceptualized.

DSM-III and DSM-III-TR Era

The provided evidence does not contain specific information about hypersomnolence disorder criteria in DSM-III or DSM-III-TR versions. These earlier editions predated the modern conceptualization of this disorder as a distinct diagnostic entity.

DSM-IV Period

During the DSM-IV era, what is now called hypersomnolence disorder was classified under different terminology, though the provided evidence does not detail the specific DSM-IV criteria. The historical distinction between "primary" and "secondary" (comorbid) insomnia and hypersomnia subtypes was utilized during this period, based on clinician assessment of whether medical or psychiatric comorbidities caused or maintained the sleep disorder 1.

DSM-5 Major Reconceptualization (2013)

DSM-5 introduced "Hypersomnolence Disorder" as the formal diagnostic term, replacing previous nomenclature and eliminating the primary versus secondary distinction 1. This represented a fundamental shift in conceptualization.

Key DSM-5 Diagnostic Criteria:

• The disorder requires excessive sleepiness despite normal sleep duration of at least 7 hours, occurring at least 3 times per week for at least 3 months 1, 2
• The sleep disturbance must cause clinically significant distress or impairment in social, occupational, or other important areas of functioning 1
• The excessive sleepiness cannot be better explained by another sleep disorder, medical condition, mental disorder, medication, or substance use 1, 2

Rationale for Eliminating Primary/Secondary Distinction:

• The decision was based on observations that cause-effect relationships between hypersomnia and co-occurring disorders are often difficult to discern 1
• Hypersomnia frequently becomes an independent disorder even when initially triggered by another medical or psychiatric condition 1

DSM-5-TR (Text Revision)

The provided evidence does not contain specific information about changes introduced in DSM-5-TR. Text revisions typically involve clarifications and updated background information rather than fundamental criteria changes.

ICD-10 Classification

The evidence does not provide specific ICD-10 diagnostic criteria for hypersomnolence disorder, though ICD-10 was contemporaneous with DSM-IV and likely maintained similar conceptual frameworks.

ICD-11 Modern Approach

ICD-11 terminology shifted to emphasize "sleep-wake" rather than solely "sleep" disorders, highlighting the significant impairments these conditions exert on daytime functioning 1. This parallels the DSM-5 reconceptualization.

ICD-11 Diagnostic Enhancements:

• Caregiver input is emphasized, particularly for diagnostic assessments among cognitively impaired and pediatric patients 1
• Objective documentation via actigraphy is recommended when possible, including both work/school and free days, to provide longitudinal sleep-wake pattern documentation 1
• Circadian phase assessments (e.g., dim light melatonin onset) are recommended if feasible 1
• De-emphasis on "conventional" and "socially acceptable" clock times, recognizing their relative nature and instead highlighting patients' subjective concerns 1

Critical Diagnostic Challenges Across All Versions

Hypersomnolence disorder remains a diagnosis of exclusion that is difficult to distinguish from narcolepsy type 2 due to symptom overlap and inadequacies of objective testing 3. This fundamental challenge has persisted across all classification systems.

Ongoing Diagnostic Limitations:

• Patients with mood disorders and hypersomnolence rarely demonstrate objective daytime sleepiness on the Multiple Sleep Latency Test (MSLT), the current gold standard 4
• Diagnostic delays of up to 9 years are common, reflecting the difficulty in establishing this diagnosis 3
• The disorder was first described in 1976 under monosymptomatic and polysymptomatic forms, yet after 45+ years remains poorly delineated 5

Common Diagnostic Pitfalls:

• Failing to rule out obstructive sleep apnea, which affects approximately 24% of older adults and is a significant cause of daytime sleepiness 6
• Missing iatrogenic causes, as many psychiatric patients are overweight and treated with sedative medications 4
• Not checking ferritin levels when restless legs syndrome symptoms are present, as levels less than 45-50 ng/mL indicate a treatable cause 1
• Overlooking medication effects, including benzodiazepines, opioids, antihistamines, antidepressants, and antipsychotics 6

Prevalence and Clinical Context

Idiopathic hypersomnia (the sleep medicine equivalent of hypersomnolence disorder) occurs in approximately 0.02%-0.010% of the general population with a mean age of onset of 21.8 years 2. This contrasts with narcolepsy's prevalence of 0.05% 6.