Validated 8-item scale for daytime sleepiness. Scores above 10 are excessive.
Source: Johns, Sleep 1991.
What does the Epworth Sleepiness Scale measure?
The Epworth Sleepiness Scale (ESS) is an 8-item self-administered questionnaire developed by Dr Murray Johns at Epworth Hospital in Melbourne, Australia and published in Sleep in 1991. It asks respondents to rate their likelihood of dozing off in eight typical daily situations, using a scale from 0 (would never doze) to 3 (high chance of dozing). Total scores range from 0 to 24.
The ESS measures chronic, habitual sleepiness, sometimes called "sleep propensity", rather than fatigue or tiredness. A high score indicates that you are prone to falling asleep in situations where most people would remain alert. This kind of excessive daytime sleepiness (EDS) is a cardinal symptom of several sleep disorders, most commonly obstructive sleep apnea, narcolepsy, and idiopathic hypersomnia.
The ESS is widely used in sleep medicine clinics as an initial screening tool and to monitor treatment response. Patients with obstructive sleep apnea who start CPAP therapy typically see their ESS score fall from the "severe" range to normal within weeks of effective treatment. The scale is also used in research as an outcome measure.
Important limitations: the ESS measures subjective sleepiness and can be influenced by insight (people with severe sleepiness sometimes underreport), mood, and cultural norms around sleeping in public. Objective sleepiness is measured with the Multiple Sleep Latency Test (MSLT), which requires an overnight sleep study.
Reference ranges
| Score | Interpretation | Action |
|---|---|---|
| 0 – 10 | Normal daytime sleepiness | No action usually needed |
| 11 – 12 | Mild excessive sleepiness | Review sleep hygiene; consider sleep study |
| 13 – 15 | Moderate excessive sleepiness | Sleep study recommended |
| 16 – 24 | Severe excessive sleepiness | Urgent sleep specialist referral |
When should you see a doctor?
An ESS score above 10, especially combined with snoring, witnessed apnoeas, morning headaches, or a high STOP-BANG score, should prompt evaluation by a doctor or sleep specialist. Untreated sleep apnea significantly raises cardiovascular risk and impairs cognitive function and driving safety. Even scores in the 11–12 range are worth discussing if they affect your daily functioning or driving safety.