What are the DSM‑5 criteria for insomnia disorder?

DSM-5 Diagnostic Criteria for Insomnia Disorder

According to DSM-5, insomnia disorder is diagnosed when a patient reports difficulty with sleep initiation, sleep maintenance, or early-morning awakening with inability to return to sleep, occurring at least 3 nights per week for at least 3 months, causing clinically significant distress or daytime impairment, despite adequate opportunity for sleep, and not better explained by another sleep, medical, mental, or substance-related disorder. 1

Core Diagnostic Requirements

A. Sleep Complaint (≥1 of the following)

• Difficulty initiating sleep 1, 2
• Difficulty maintaining sleep (frequent or prolonged nocturnal awakenings) 1, 2
• Early-morning awakening with inability to return to sleep 1, 2
• Chronically nonrestorative or poor-quality sleep 3

B. Adequate Sleep Opportunity

• The sleep difficulty must occur despite having adequate opportunity and circumstances for sleep—meaning the patient has sufficient time allocated for sleep and an appropriate sleep environment 1, 2

C. Daytime Consequences (≥1 required)

• Fatigue or malaise 3
• Impaired attention, concentration, or memory 3
• Social, vocational, educational, or behavioral dysfunction 3, 1
• Mood disturbance or irritability 3
• Daytime sleepiness 3
• Reduced motivation, energy, or initiative 3
• Proneness to errors or accidents at work or while driving 3
• Tension headaches or gastrointestinal symptoms in response to sleep loss 3
• Concerns or worries about sleep 3

D. Frequency and Duration Thresholds

• Symptoms must occur at least 3 nights per week 1, 2
• Duration must be at least 3 months for chronic insomnia disorder 1, 2
• These quantitative thresholds reduce diagnostic variability and improve inter-rater reliability 4

E. Exclusion Criteria

• The sleep disturbance is not better explained by another sleep disorder (e.g., obstructive sleep apnea, restless legs syndrome, circadian rhythm sleep-wake disorder, parasomnia) 1, 5
• The insomnia does not occur exclusively during the course of another mental disorder 1
• The insomnia is not attributable to the physiological effects of a substance (medication, drug of abuse) or another medical condition 1

Key Conceptual Changes in DSM-5

Elimination of Primary/Secondary Distinction

• DSM-5 removed the outdated primary versus secondary insomnia classification, recognizing that insomnia is an independent disorder that may coexist with—but is not merely secondary to—medical or psychiatric conditions 2, 6, 7
• Insomnia and comorbid conditions have a bidirectional, interactive relationship rather than a hierarchical cause-effect relationship 8, 2, 7
• Clinicians should document insomnia disorder and any co-occurring psychiatric or medical diagnoses as separate, co-existing conditions 2

Unified Diagnostic Category

• The term "Insomnia Disorder" consolidates previous subtypes (psychophysiological insomnia, paradoxical insomnia, idiopathic insomnia) into a single diagnostic category 2, 4
• This harmonization across DSM-5, ICD-11, and ICSD-3 reduces diagnostic confusion and improves consistency 2, 4

Clinical Assessment Essentials

Minimum Documentation Required

• A 2-week sleep diary documenting bedtime, sleep-onset latency, number and duration of awakenings, wake after sleep onset, time in bed, total sleep time, and sleep efficiency should be obtained before confirming diagnosis 4
• Assessment must include evaluation of daytime functional impairment in social, occupational, educational, or behavioral domains 4
• Screen for perpetuating factors including maladaptive sleep behaviors (excessive time in bed), dysfunctional beliefs about sleep ("I must get 8 hours or I'll be ruined"), and conditioned arousal 4

Differential Diagnosis Considerations

• Persistent insomnia beyond 7–10 days of treatment warrants evaluation for comorbid sleep disorders such as obstructive sleep apnea, restless legs syndrome, periodic limb movement disorder, or circadian rhythm disorders 8, 4
• Paradoxical insomnia (severe subjective complaint with minimal objective disturbance on polysomnography) requires different management than psychophysiological insomnia, though DSM-5 does not differentiate these presentations 4
• Insomnia symptoms are common in other sleep disorders (e.g., sleep apnea, circadian rhythm disorders), making it sometimes difficult to determine whether the patient has insomnia disorder or whether symptoms are purely due to another sleep disorder 5

Diagnostic Limitations and Pitfalls

Lack of Phenotypic Specificity

• DSM-5 criteria do not differentiate sleep-onset, sleep-maintenance, or early-morning awakening subtypes, which have distinct pharmacologic treatment implications (e.g., zaleplon for onset vs. doxepin for maintenance) 4

Absence of Severity Gradations

• No formal mild, moderate, or severe ratings are provided based on frequency of affected nights or degree of daytime impairment 4

Reliance on Self-Report

• Insomnia disorder diagnosis primarily rests on self-report; objective measures like actigraphy or polysomnography are not part of routine diagnostic criteria but play an important role in research and differential diagnosis 9

Special Population Considerations

• ICD-11 emphasizes caregiver input when assessing insomnia in cognitively impaired adults and pediatric patients, a consideration not explicitly detailed in DSM-5 2