What is the clinical approach to diagnose insomnia?

Clinical Diagnosis of Insomnia

Insomnia is primarily diagnosed through clinical evaluation consisting of a thorough sleep history combined with detailed medical, substance, and psychiatric histories—polysomnography is NOT indicated for routine diagnosis. 1

Diagnostic Criteria

The diagnosis requires BOTH components to be present: 1, 2

• Nighttime symptoms: Difficulty initiating sleep, difficulty maintaining sleep, or early morning awakening
• Daytime dysfunction: The sleep disturbance must cause clinically significant distress or impairment in daytime functioning (fatigue, mood disturbances, cognitive difficulties, reduced quality of life)

For chronic insomnia specifically, symptoms must occur ≥3 nights per week and persist ≥3 months. 2

Essential Clinical Evaluation Components

Initial Screening Questions

Begin with two screening questions recommended by the American Academy of Sleep Medicine: 3

• "Do you have problems with your sleep or sleep disturbance on average for three or more nights a week?"
• "Does the problem with your sleep negatively affect your daytime functioning?"

If both answers are yes, proceed with comprehensive assessment. 3

Comprehensive Sleep History

The sleep history must systematically cover: 1, 4

• Specific insomnia complaints: Sleep onset latency, number and duration of awakenings, early morning awakening, total sleep time
• Pre-sleep conditions: Bedtime routines, behaviors in bed (TV watching, phone use, "clock watching"), anticipatory anxiety about sleep, bedroom environment (light, noise, temperature)
• Sleep-wake patterns: Bedtimes, wake times, day-to-day variability, weekend vs. weekday differences
• Daytime consequences: Distinguish fatigue (more common in insomnia) from sleepiness (suggests other sleep disorders like sleep apnea), mood disturbances, cognitive difficulties, quality of life impact 1, 2
• Napping patterns: Frequency, duration, timing, voluntary vs. involuntary 1

Medical, Psychiatric, and Substance History

Conduct systematic review of: 1

• Medical conditions: Cardiovascular disease, pulmonary conditions, chronic pain, gastrointestinal disorders, endocrine disorders, neurological conditions 3
• Psychiatric disorders: Depression, anxiety, bipolar disorder, PTSD (insomnia rates 50-75% in these populations) 1, 3
• Medications: Beta-blockers, bronchodilators, corticosteroids, decongestants, diuretics, SSRIs, SNRIs 1, 3
• Substances: Caffeine, alcohol, nicotine, over-the-counter sleep aids, recreational drugs 1, 3

Physical and Mental Status Examination

Perform examination to identify comorbid conditions and aid differential diagnosis. 1 This is particularly important for detecting signs of sleep apnea, movement disorders, or medical conditions contributing to insomnia.

Required Minimum Documentation

At minimum, every patient must complete: 1

1. Two-week sleep diary/log: Document bedtime, wake time, sleep onset latency, number and duration of awakenings, total sleep time, nap frequency and duration, sleep quality ratings 1, 3
2. Epworth Sleepiness Scale: To identify excessive sleepiness and rule out comorbid sleep disorders like sleep apnea 1, 3
3. General medical/psychiatric questionnaire: To systematically identify comorbid disorders 1

Optional Assessment Tools

Additional instruments that may aid diagnosis include: 1, 3

• Insomnia Severity Index: Validated tool to identify insomnia cases and assess treatment effects 3
• Actigraphy: For ≥7 days to objectively measure sleep-wake patterns, particularly when circadian rhythm disorders are suspected 1, 3
• Measures of subjective sleep quality, psychological assessment scales, daytime function scales, quality of life measures 1

When Polysomnography IS Indicated

Polysomnography is NOT routine but IS indicated when: 1

• Reasonable clinical suspicion of sleep apnea (snoring, witnessed apneas, morning headaches, excessive daytime sleepiness)
• Suspicion of periodic limb movement disorder or restless legs syndrome
• Initial diagnosis is uncertain after clinical evaluation
• Treatment fails (behavioral or pharmacologic)
• Precipitous arousals with violent or injurious behavior occur

Critical Diagnostic Pitfalls to Avoid

Do not confuse fatigue with sleepiness: Fatigue (low energy, tiredness, weariness) is the predominant complaint in chronic insomnia, whereas true sleepiness (tendency to fall asleep) suggests alternative sleep disorders like sleep apnea. 1, 2

Avoid excessive laboratory testing: Blood work and radiographic studies are not indicated for routine insomnia evaluation unless there is suspicion for specific comorbid disorders. 1

Recognize multiple conditions may coexist: The presence of one insomnia disorder does not exclude others—multiple primary and comorbid insomnia disorders can occur simultaneously. 1, 2

Obtain bed partner input: Collateral history is crucial as bed partners may observe symptoms the patient is unaware of, including snoring, breathing pauses, limb movements, and parasomnias. 4

Differential Diagnosis Considerations

Distinguish between: 1, 3

• Primary insomnia disorders: Psychophysiological insomnia, paradoxical insomnia, idiopathic insomnia
• Comorbid insomnia: Due to mental disorders, medical conditions, medications/substances
• Other sleep disorders: Obstructive sleep apnea, restless legs syndrome, circadian rhythm disorders
• Inadequate sleep hygiene: Irregular sleep scheduling, use of stimulants, non-sleep behaviors in bed environment

The diagnosis is fundamentally clinical, relying on structured history-taking and systematic documentation rather than laboratory testing or polysomnography in the vast majority of cases. 1