Epworth Sleepiness Scale (ESS)
The Epworth Sleepiness Scale is an 8-item self-administered questionnaire that measures a person's general level of daytime sleepiness by rating the likelihood of dozing off in common daily situations, with scores ranging from 0-24 where scores >10 indicate excessive daytime sleepiness. 1
How the ESS is Scored
The questionnaire asks patients to rate their chance of dozing off in eight specific situations using a 0-3 scale 1:
- 0 = would never doze
- 1 = slight chance of dozing
- 2 = moderate chance of dozing
- 3 = high chance of dozing
The Eight Situations Assessed:
- Sitting and reading
- Watching TV
- Sitting inactive in a public place (theater or meeting)
- As a passenger in a car for an hour without a break
- Lying down to rest in the afternoon when circumstances permit
- Sitting and talking to someone
- Sitting quietly after lunch without alcohol
- In a car, while stopped for a few minutes in traffic
The total score is calculated by summing all eight responses, yielding a range of 0-24 points. 1
Interpretation of Results
- Scores 0-10: Normal range, no excessive daytime sleepiness 2
- Scores >10: Indicates excessive daytime sleepiness 3
- Scores ≥11: Considered abnormal and warrant further clinical evaluation 4
Important Clinical Caveats
Limitations You Must Understand:
The ESS cannot confirm or exclude sleepiness on its own and should never be used as a standalone diagnostic tool. 4 Multiple guidelines emphasize critical limitations:
- High ESS scores (>17) are insufficient to identify high-risk drivers - direct clinical questioning is mandatory 4
- The ESS has poor diagnostic performance for OSA, with sensitivity ranging only 0.27-0.72 and specificity 0.50-0.76, producing excessive false negatives 5
- Individual scores vary considerably within the same patient (limits of agreement -6.7 to +7.5), though classification as normal vs. sleepy shows better reliability (Cohen's kappa 0.67) 6
Administration Method Matters:
Physician-administered ESS scores are systematically higher and more accurate than self-administered versions. When physicians administer the questionnaire, scores average 1.7-2.0 points higher and correlate better with objective sleep measures 7, 8. Self-administration results in 23% of questionnaires being improperly completed versus 0% with physician administration 7.
Clinical Applications
Appropriate Uses:
- Screening tool to prompt direct clinical questioning about sleepiness 4
- Monitoring treatment response in sleep disorders - expect ≥2 point improvement with effective CPAP therapy 9
- Baseline assessment as part of comprehensive sleep evaluation (minimum requirement alongside medical/psychiatric questionnaire and 2-week sleep log) 3
- Follow-up monitoring at each patient visit for those with hypersomnias 9
When ESS Should NOT Be Used:
- As a standalone diagnostic test for OSA or other sleep disorders 5
- To determine driving risk without direct clinical assessment 4
- As the sole measure to exclude sleepiness in safety-sensitive situations 4
Practical Clinical Algorithm
When using the ESS in practice:
- Administer the questionnaire (preferably physician-administered for accuracy)
- If ESS >10: Initiate direct questioning about unintentional sleep episodes during daily activities and any motor vehicle crashes/near-misses
- If ESS ≥11: Consider this a prompt for comprehensive sleep evaluation, not a diagnosis
- For monitoring: Repeat at follow-up visits; expect ≥2 point improvement with effective therapy
- Never rely on ESS alone - always combine with clinical history, physical examination, and objective testing when indicated
The ESS has demonstrated good internal consistency (Cronbach's alpha 0.82) across multiple studies and languages 10, with test-retest reliability showing paired scores highly correlated (r=0.82) over 5 months in stable patients 11.