What evaluation should be performed to rule out obstructive sleep apnea, restless‑legs syndrome, periodic limb movement disorder, and circadian‑rhythm disorders when insomnia persists after a 7‑ to 10‑day trial of first‑line therapy?

Evaluation for Underlying Sleep Disorders in Treatment-Resistant Insomnia

When insomnia persists after 7-10 days of first-line therapy, perform polysomnography if there is reasonable clinical suspicion of obstructive sleep apnea or periodic limb movement disorder, use actigraphy to characterize circadian rhythm patterns, and conduct targeted clinical assessments including the Epworth Sleepiness Scale and specific symptom questionnaires for restless legs syndrome. 1

Clinical Assessment Tools

Mandatory Initial Evaluation

• Epworth Sleepiness Scale to identify excessive daytime sleepiness and comorbid disorders of sleepiness 1
• Two-week sleep log to identify sleep-wake patterns and day-to-day variability 1
• Targeted clinical interview focusing on symptoms specific to each suspected disorder 1

Obstructive Sleep Apnea Screening

• Use STOP-BANG questionnaire or similar validated screening tools 1
• Assess for characteristic symptoms: excessive snoring, gasping for air, observed apneas, frequent arousals, and unexplained daytime drowsiness 1
• Polysomnography is indicated when there is reasonable clinical suspicion of sleep-related breathing disorders 1
• Consider overnight oximetry as an initial screening measure with referral to respiratory or ENT sleep clinic 1

Restless Legs Syndrome Evaluation

• Conduct in-depth questioning about uncomfortable sensations in legs with urge to move, worsening at rest, relief with movement, and circadian pattern (worse in evening/night) 1
• Measure serum ferritin levels; supplementation is indicated if below 75 ng/ml, as this is associated with improved symptoms 1
• Note that RLS has a circadian rhythmicity and most patients present with sleep initiation and/or maintenance insomnia 2

Periodic Limb Movement Disorder Assessment

• Polysomnography is indicated when there is reasonable clinical suspicion of movement disorders 1
• This is the only definitive method to diagnose periodic limb movements during sleep, as increased PLMS is a supportive criterion in diagnosis 2, 3
• Clinical history should include questions about sudden involuntary movements of arms or legs during sleep 1

Circadian Rhythm Disorder Evaluation

• Actigraphy is indicated as a method to characterize circadian rhythm patterns in individuals with insomnia 1
• Use sleep logs for at least two weeks to identify patterns of sleep-wake times and day-to-day variability 1, 4
• Consider the Morningness-Eveningness Questionnaire, though there is insufficient evidence for routine clinical use 4
• Assess for shift work, jet lag, irregular sleep-wake patterns, or symptoms of advanced/delayed sleep phase 4
• Circadian phase markers (such as dim light melatonin onset) are useful to confirm diagnosis of free-running disorder but have insufficient evidence for routine use in other circadian disorders 4

When Polysomnography Is NOT Indicated

Polysomnography and MSLT are not indicated in the routine evaluation of chronic insomnia, including insomnia due to psychiatric or neuropsychiatric disorders 1. This is a Standard-level recommendation, meaning routine use would be inappropriate 1.

When Polysomnography IS Indicated

Polysomnography becomes indicated under specific circumstances 1:

• Reasonable clinical suspicion of breathing disorders (sleep apnea)
• Reasonable clinical suspicion of movement disorders (periodic limb movements, RLS)
• Initial diagnosis is uncertain
• Treatment fails (behavioral or pharmacologic) after 7-10 days
• Precipitous arousals occur with violent or injurious behavior

Additional Considerations

Comorbidity Recognition

Multiple sleep disorders may coexist with insomnia, and the presence of one insomnia disorder does not exclude others 1, 5. For example, comorbid insomnia and sleep apnea (COMISA) is a recognized entity 5.

Daytime Sleepiness as a Red Flag

The presence of significant sleepiness (actual tendency to fall asleep, not just fatigue) should prompt a search for other potential sleep disorders, as feelings of fatigue are more common than true sleepiness in primary insomnia 1. This distinction is critical for appropriate differential diagnosis.

Reevaluation for Occult Disorders

When treatment has been ineffective, reevaluation for occult comorbid disorders should be considered 1. This aligns with the recommendation to further evaluate patients whose insomnia does not remit within 7-10 days of treatment 1.