Understanding the Epworth Sleepiness Scale

What Is the Epworth Sleepiness Scale?

The Epworth Sleepiness Scale (ESS) is a short questionnaire developed in 1991 by Dr. Murray Johns at Epworth Hospital in Melbourne, Australia. It asks you to rate how likely you are to doze off in eight everyday situations. The total score ranges from 0 to 24.

Doctors and sleep specialists use the ESS as a quick screening tool to measure subjective daytime sleepiness. It does not diagnose any condition, but a high score can signal that a conversation with a healthcare provider is worthwhile.

Take the Epworth Sleepiness Scale now to see where you fall.

The Eight Situations

The ESS asks you to rate your usual chance of dozing off in eight everyday situations:

1. Sitting and reading
2. Watching TV
3. Sitting (inactive) in a public place (like a meeting or dinner event)
4. Sitting in a car as the passenger for one consecutive hour without breaks
5. Lying down to rest during the daytime
6. Sitting and talking to another person
7. Sitting after eating a meal (alcohol not included)
8. Driving a car while stopped in traffic for a few minutes

The eight situations were deliberately chosen to span a range of soporific influence: situations like reading or watching TV are weakly soporific, while sitting after a meal or as a long-distance passenger are moderately so. Combining the eight gives a more stable estimate of average daytime sleepiness than asking a single question like "are you sleepy?"

How the Scoring Works

Each of the eight situations is rated on a 0 to 3 scale:

• 0 means you would never doze in that situation
• 1 means there is a slight chance you would doze
• 2 means there is a moderate chance
• 3 means there is a high chance

The scores are added together for a total between 0 and 24.

If a situation does not apply (you do not drive, for example), most clinicians ask you to estimate how you would feel if you did. Skipping items affects the validity of the total score.

What Your Score Means

Johns reported in 1991 that healthy adults typically scored 10 or below; scores of 11 or higher have since been adopted as the clinical threshold for excessive daytime sleepiness (EDS). Many clinicians use a finer-grained breakdown to give patients a more nuanced read on their sleepiness. These are guidelines, not diagnoses.

0 to 7: Unlikely abnormal sleepiness. Your daytime alertness is well within the range most people report. Feeling sleepy in a warm room after lunch is not the same as problematic sleepiness.

8 to 10: Average sleepiness. This is the population average. Most adults fall somewhere in this range. It does not indicate a sleep disorder.

11 to 15: Possible excessive sleepiness. You are at or above the canonical clinical cutoff (≥11) for EDS. This does not mean you have a sleep disorder, but it is worth discussing with a healthcare provider, especially if the sleepiness affects your daily life, your driving, or your work.

16 to 24: Significant excessive sleepiness. Scores in this range suggest substantial daytime sleepiness. A conversation with a healthcare provider about your sleep quality is strongly recommended. They may suggest a sleep study to look for underlying causes.

The Cleveland Clinic uses a slightly different breakdown (mild EDS at 11-12, moderate at 13-15, severe at 16-24); the underlying scale and the ≥11 EDS threshold are the same across sources.

How Reliable Is the ESS?

Johns' original 1991 validation study reported strong test-retest reliability: ESS scores in healthy medical students were very similar across testings spaced five months apart. Subsequent studies measured the intraclass correlation coefficient between 0.81 and 0.93 across five separate investigations.

Reliability is more variable in clinical populations. A 2022 systematic review concluded that the ESS shows good internal consistency overall, but test-retest reliability within short time windows in clinical settings is lower than the original validation suggested. The practical takeaway: a single ESS score is a useful screening signal, but a second measurement weeks or months later is the right way to confirm a meaningful change in sleepiness, not a same-week repeat.

What the ESS Does Not Tell You

The ESS measures how sleepy you feel during the day. It does not:

• Diagnose sleep apnea or any other sleep disorder
• Measure sleep quality, sleep architecture, or sleep duration
• Replace a sleep study
• Account for caffeine, medications, or shift work that may mask or amplify sleepiness

A normal ESS score does not rule out sleep apnea. Many people with sleep apnea report low ESS scores because they have adapted to chronic sleepiness, or because caffeine masks the symptoms. If your partner notices loud snoring, gasping, or breathing pauses during sleep, a screening conversation with your doctor is still important regardless of your ESS score.

ESS vs Objective Sleepiness Tests

The ESS is a subjective measure: it captures how sleepy you perceive yourself to be. Two objective tests measure sleepiness directly in a sleep lab:

• MSLT (Multiple Sleep Latency Test): measures how quickly you fall asleep during four or five 20-minute nap opportunities scheduled across a day. A short average sleep latency is the gold-standard objective sign of EDS and is required to diagnose narcolepsy.
• MWT (Maintenance of Wakefulness Test): measures how long you can stay awake during scheduled trials. Used to assess fitness for safety-critical work like commercial driving and aviation.

The correlation between ESS scores and MSLT-measured sleepiness is statistically significant but only modest. Many clinical studies find the two measures only weakly aligned. The practical implication: a high ESS warrants further investigation but does not predict an abnormal MSLT, and a normal ESS does not rule out an abnormal MSLT. Both subjective and objective measures contribute to a complete picture of daytime sleepiness.

Limitations to Keep in Mind

• Self-report bias. Like any questionnaire, the ESS is vulnerable to social-desirability bias (under-reporting sleepiness to seem normal) and to misinterpretation of "dozing" (some respondents distinguish "drifting off" from "actually sleeping"; the scale treats them the same).
• Cultural and language variability. Translations of the ESS into more than 50 languages have produced varied psychometric properties across countries. Concepts like "sitting in a public place" or "as a passenger for an hour" carry different connotations in different cultures.
• Adaptation effect. People with chronic untreated sleep apnea often score in the normal range because they have lived with daytime sleepiness for years and no longer perceive it as abnormal.
• Caffeine and shift work. Heavy caffeine use can mask sleepiness; night-shift workers may score normally despite genuine sleep deprivation because their "daytime" looks different.

Pediatric Version (ESS-CHAD)

A pediatric adaptation called the Epworth Sleepiness Scale for Children and Adolescents (ESS-CHAD) substitutes age-appropriate situations (sitting in class, doing homework, eating a meal) for the adult versions and uses the same 0-3 scoring. The ESS-CHAD was validated in adolescents aged 12-18 by Janssen et al. (2017, Rasch analysis); a separate validation in pediatric narcolepsy patients aged 7-16 supports its use in younger children. Children younger than about 9 typically need a parent's help; older children and most adolescents can complete it independently.

If you are using the ESS for a child, use the ESS-CHAD form rather than the adult version. The two are not interchangeable.

When to See a Doctor

Consider scheduling an appointment if:

• Your ESS score is 10 or higher
• You feel unrefreshed after a full night of sleep
• You struggle to stay awake while driving or at work
• A bed partner has noticed snoring, gasping, or pauses in your breathing
• You wake up with headaches or a dry mouth regularly

Your doctor can determine whether a home sleep test or in-lab study is appropriate based on your symptoms and history. Bringing your ESS score to the appointment gives your provider a concrete data point to work with rather than a vague description of "feeling tired." You can also take the STOP-BANG screener to assess your sleep apnea risk alongside your sleepiness level.

How Doctors Use the ESS

Sleep physicians use the ESS at multiple points in your care. At the initial consultation, it helps establish a baseline: how sleepy are you before treatment? After starting CPAP therapy, a follow-up ESS can quantify improvement. A score that drops from 14 to 6 after three months of treatment gives both you and your provider concrete evidence that therapy is working.

The ESS is also used in research. Studies comparing treatment outcomes frequently use ESS changes as a primary measure of clinical improvement. Because the scale is validated and standardized, scores are comparable across patients and clinics. This is why your doctor may ask you to fill it out at every annual sleep appointment.

Insurance companies may also reference ESS scores when reviewing CPAP compliance and medical necessity. A documented high baseline score strengthens the clinical case for treatment.

Using the ESS with CPAP Therapy

If you already use a CPAP machine, the ESS can help you and your doctor gauge whether your therapy is effectively reducing daytime sleepiness. A high ESS score despite consistent CPAP use could indicate that your pressure settings need adjustment, your mask fit is compromising therapy, or there is another factor worth investigating.

You can analyze your CPAP data to see whether your nightly metrics align with how you feel during the day. Comparing your ESS score against your objective therapy data (AHI, usage hours, leak rate) gives you a complete picture of both how your therapy is performing and how it is affecting your daily life.

Sources

• Johns MW. A new method for measuring daytime sleepiness: the Epworth Sleepiness Scale. Sleep. 1991;14(6):540-545.
• Walker NA, Sunderram J, Zhang P, Lu SE, Scharf MT. Reliability and Efficacy of the Epworth Sleepiness Scale: Is There Still a Place for It? Nature and Science of Sleep. 2022;14:2233-2240. PubMed Central (opens in new tab)
• Cleveland Clinic. Epworth Sleepiness Scale (ESS): What It Is & Results. (opens in new tab)
• Janssen KC, Phillipson S, O'Connor J, Johns MW. Validation of the Epworth Sleepiness Scale for Children and Adolescents using Rasch analysis. Sleep Medicine. 2017;33:30-35. (Validates ESS-CHAD in adolescents 12-18.)
• Berry RB et al. Validation of the Epworth Sleepiness Scale for Children and Adolescents (ESS-CHAD) questionnaire in pediatric patients with narcolepsy with cataplexy aged 7-16 years. Sleep Medicine. 2022;90:204-211. (Extends ESS-CHAD validity to children as young as 7 in pediatric narcolepsy populations.)
• Harvard Medical School Division of Sleep Medicine. Epworth Sleepiness Scale. (opens in new tab)

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