What is the recommended workup for a patient with excessive daytime sleepiness?

Workup for Excessive Daytime Sleepiness

Begin by quantifying sleepiness severity with the Epworth Sleepiness Scale, obtaining a detailed sleep history including bed partner input, and systematically ruling out obstructive sleep apnea and medication-induced causes before considering primary central disorders of hypersomnolence. 1, 2

Initial Clinical History

Key questions to address:

• Document sleepiness characteristics: Establish onset, frequency, duration, and any remission periods of excessive daytime sleepiness 3, 1
• Verify adequate sleep duration: Confirm nighttime sleep is truly sufficient (typically 7-9 hours for adults) to exclude simple sleep deprivation as the cause 1, 2
• Screen for narcolepsy features: Ask specifically about cataplexy (sudden muscle weakness with emotion), sleep paralysis, hypnagogic hallucinations, and automatic behaviors 3, 1
• Assess for other sleep disorders: Question about witnessed apneas, snoring, restless leg symptoms, and napping patterns (including whether naps are refreshing) 3, 1
• Complete medication review: Document all prescription medications, over-the-counter drugs, recreational substances, and alcohol use—sedating medications are a common and frequently overlooked cause 3, 2
• Medical/psychiatric history: Obtain comprehensive medical, neurologic, and psychiatric histories to identify conditions causing secondary hypersomnia 3, 1
• Obtain bed partner history: Interview the bed partner separately when possible, as they may provide critical information the patient cannot 3

Complete the Epworth Sleepiness Scale to objectively quantify sleepiness severity 3, 1

Have patient maintain a 2-week sleep diary documenting sleep-wake times, sleep quality, napping, daytime impairment, medications, caffeine/alcohol intake, and day-to-day variability 3, 1

Physical and Neurological Examination

Perform thorough neurological evaluation to identify CNS pathology that could cause hypersomnia, including assessment for Parkinson's disease, stroke sequelae, or other neurological conditions 3, 1, 2

Assess cognition as cognitive impairment can indicate underlying neurodegenerative disease or help monitor treatment response 3, 1

Laboratory Testing

Order essential blood work to exclude metabolic and endocrine causes: 3, 1

• Thyroid stimulating hormone (TSH) to rule out hypothyroidism
• Complete blood count (CBC) to assess for anemia
• Comprehensive metabolic panel including liver function tests
• Serum chemistry to identify electrolyte abnormalities

Sleep Studies (Mandatory Objective Testing)

Overnight polysomnography (PSG) is the mandatory first objective test to rule out sleep-disordered breathing and other conditions disrupting nighttime sleep—obstructive sleep apnea affects over 50% of patients with excessive sleepiness in some populations and must be excluded first 3, 1, 2

Multiple Sleep Latency Test (MSLT) follows PSG the next day and involves 4-5 daytime naps at 2-hour intervals with measurement of sleep onset latency and sleep type 3, 1, 2

MSLT interpretation: 3, 1

• Mean sleep latency ≤8 minutes indicates pathological sleepiness
• REM sleep on ≥2 naps is diagnostic of narcolepsy
• Mean sleep latency ≤8 minutes with <2 sleep-onset REM periods suggests idiopathic hypersomnia

Critical caveat: Common medications used in older adults and chronic conditions can complicate interpretation of these studies—review and potentially hold sedating medications before testing when medically appropriate 3

Advanced Testing (When Indicated)

Brain MRI is indicated when: 3, 1, 2

• Neurological examination is abnormal
• Narcolepsy without cataplexy is suspected
• To identify structural lesions (tumors, multiple sclerosis, strokes, intracranial bleeds) causing hypersomnia

Cerebrospinal fluid hypocretin levels can confirm narcolepsy with cataplexy when MSLT is unavailable or results are equivocal 3, 1

Differential Diagnosis Framework

Most common causes to systematically exclude: 2, 4

1. Insufficient sleep/sleep deprivation (verify with sleep diary)
2. Obstructive sleep apnea (requires PSG)
3. Medication-induced hypersomnia (benzodiazepines, opioids, antihistamines, certain antidepressants, CNS depressants)
4. Medical conditions: Hypothyroidism, anemia, hepatic encephalopathy
5. Neurological conditions: Parkinson's disease, stroke, multiple sclerosis, traumatic brain injury, early Alzheimer's disease
6. Psychiatric disorders: Depression, bipolar disorder
7. Other sleep disorders: Restless legs syndrome, periodic limb movements, chronic insomnia
8. Circadian rhythm disorders: Shift work disorder, delayed sleep phase

Primary central disorders of hypersomnolence (diagnosed only after excluding above): 3, 2

• Narcolepsy type 1 (with cataplexy)
• Narcolepsy type 2 (without cataplexy)
• Idiopathic hypersomnia

Important note: Polysomnography and MSLT are NOT indicated for routine evaluation of chronic insomnia—they are specifically for evaluating excessive daytime sleepiness and suspected sleep-disordered breathing or central hypersomnolence 3