Falling asleep while working: Medical workup for excessive sleepiness

Dozing off during the workday—whether at your desk, in meetings, or while driving—can be frustrating at best and dangerous at worst. If you regularly find yourself unable to stay awake during tasks, it’s time to explore the medical workup for excessive daytime sleepiness (EDS).

What is excessive daytime sleepiness?

Excessive daytime sleepiness means you feel an overwhelming urge to sleep when you should be alert. Common signs include:

• Nodding off during meetings, while reading, or at your computer
• Difficulty concentrating or remembering details
• Dozing off during passive activities (e.g., watching videos)
• Needing caffeine or naps to get through the afternoon

Initial evaluation

A thorough history and simple questionnaires guide the next steps.

1. Detailed sleep history

Ask yourself or your doctor:

• How many hours of sleep do you get nightly?
• Do you wake up frequently or feel unrested?
• Have you gained weight, started new medications, or changed work hours?
• Do you snore, gasp, or stop breathing at night?

2. Sleep diaries and logs

Keeping a two-week diary of sleep/wake times helps identify patterns. Note naps, caffeine/alcohol intake, and work shifts.

3. Epworth Sleepiness Scale (ESS)

The ESS is a validated 8-question score (Johns MW, 1991) that measures your chance of dozing off in everyday situations. Scores above 10 suggest significant sleepiness and warrant further workup.

Physical examination

Your doctor will look for:

• Signs of obesity, large neck circumference (risk factors for sleep apnea)
• Heart or lung issues (which can reduce sleep quality)
• Neurologic findings (e.g., muscle weakness, reflex changes)
• Thyroid enlargement or other metabolic clues

Initial laboratory tests

Basic blood tests can identify common contributors:

• Complete blood count (anemia)
• Thyroid-stimulating hormone (hypothyroidism)
• Blood glucose and HbA1c (diabetes)
• Liver and kidney function (metabolic causes)

Depending on history, your physician may check:

• Iron studies (iron-deficiency anemia)
• Vitamin D levels
• Testosterone or cortisol (endocrine causes)

When to consider sleep studies

If history, exam, and labs don’t fully explain your sleepiness—or if you have snoring, witnessed apneas, or restless legs—move on to sleep testing.

1. Polysomnography (overnight sleep study)

Practice parameters (Chesson AL Jr et al., 2005) recommend in‐lab polysomnography when you have:

• Loud, chronic snoring with daytime sleepiness
• Pauses in breathing reported by bedtime partner
• Unexplained gasping or choking at night
• Suspected periodic limb movements

This test records brain waves, breathing, oxygen levels, leg movements, and more.

2. Multiple Sleep Latency Test (MSLT)

If narcolepsy or idiopathic hypersomnia is suspected, an MSLT follows an overnight polysomnogram. You take five nap opportunities to measure how quickly you fall asleep and whether you enter REM sleep abnormally fast.

Differential diagnoses

Excessive sleepiness can stem from many conditions. Common causes include:

• Obstructive sleep apnea (repeated airway collapse during sleep)
• Narcolepsy (daytime sleep attacks, cataplexy)
• Idiopathic hypersomnia (excessive sleep without other disorders)
• Circadian rhythm disorders (shift-work, jet lag)
• Restless legs syndrome or periodic limb movement disorder
• Medication side effects (antihistamines, antidepressants)
• Depression or anxiety
• Chronic medical conditions (heart failure, COPD, kidney disease)

Additional specialized tests

Based on initial findings, your doctor may order:

• Actigraphy (wrist device that tracks sleep/wake patterns)
• Overnight oximetry (home oxygen monitoring)
• Video-EEG (to rule out nocturnal seizures)
• Specialized blood tests (autoimmune panels, genetic tests)

Stepwise workup summary

1. Screen for lifestyle and medical contributors
2. Use ESS to quantify sleepiness
3. Perform physical exam and basic labs
4. If risk factors for sleep apnea or other sleep disorders exist, obtain in-lab polysomnography
5. For persistent daytime sleepiness after polysomnography, proceed to MSLT
6. Refer to sleep specialist or neurologist for complex cases

Self-assessment and next steps

If you’re unsure what’s driving your daytime drowsiness, you might consider doing a free, online symptom check for to help organize your concerns before your doctor’s visit.

When to seek urgent help

Some situations require immediate medical attention:

• Falling asleep while driving or operating machinery
• Witnessed long pauses in your breathing during sleep
• Sudden weakness with strong emotions (possible narcolepsy cataplexy)
• Chest pain or severe shortness of breath

If you experience any of these, seek care promptly.

Working with your doctor

• Bring your sleep diary and ESS score to the appointment
• List all medications, supplements, and caffeine intake
• Describe your typical sleep environment (noise, light, temperature)
• Be honest about alcohol or drug use

Diagnostic testing and a clear treatment plan—whether CPAP for sleep apnea, lifestyle changes, medication for narcolepsy, or cognitive behavioral therapy—can restore your daytime alertness and protect your health.

Speak to a doctor about any life-threatening or serious symptoms. Early evaluation and treatment of excessive sleepiness can improve safety, performance, and quality of life.