ESSValidated Hypersomnolence Screening Tool
Situational Assessment
1. Sitting and reading
2. Watching TV
3. Sitting inactive in a public place
4. As a passenger in a car for an hour
5. Lying down to rest in the afternoon
6. Sitting and talking to someone
7. Sitting quietly after lunch (no alcohol)
8. In a car, while stopped for a few minutes
Awaiting Input
Please complete all 8 scenarios to generate the total sleepiness index and clinical guidance.
Guidelines & Evidence
Verified
Last Review: 2026-07-17
When to Use
What the ESS Measures
The ESS measures a person's "average sleep propensity" (ASP) — their usual tendency to doze off or fall asleep in daily life, not their feelings of fatigue or transient drowsiness. Unlike the Karolinska Sleepiness Scale (which measures momentary alertness), the ESS captures a stable trait over weeks to months. It specifically distinguishes dozing behavior (falling asleep) from "weariness from exertion" (fatigue), which are often confused. The eight items were chosen a priori to represent activities with widely varying "somnificity" (sleep-inducing potential), from low (sitting and talking to someone) to high (lying down to rest in the afternoon).
Primary Indications
Obstructive Sleep Apnea (OSA) – Screening for excessive daytime sleepiness; monitoring response to CPAP therapy; MCID for improvement is 2-3 points
Narcolepsy – Quantifying severe hypersomnolence (ESS usually 16-24); distinguishing from normal sleepiness (specificity >95% at score >15)
Idiopathic Hypersomnia – Initial assessment and treatment monitoring (stimulants, sodium oxybate)
Shift Work Disorder – Documenting excessive sleepiness in night shift workers
Multiple Sclerosis-related fatigue – Differentiating sleepiness from fatigue (ESS specifically measures dozing, not weariness)
Parkinson's Disease – Screening for excessive daytime sleepiness (common non-motor symptom)
Pre-driving risk assessment – Very high scores (>15) may indicate increased drowsy driving risk, but ESS should NOT be used alone for license decisions
Clinical trial endpoint – Common primary or secondary outcome in sleep disorder interventions
Pre-procedural screening (e.g., bariatric surgery, sedation) – Identifying undiagnosed OSA risk (high ESS prompts sleep study)
Interpretation of Score Ranges (Per Official ESS Guidelines)
| Score Range | Classification | Clinical Significance | Typical Populations |
|---|---|---|---|
| 0-5 | Lower Normal Daytime Sleepiness | Rarely or never dozes in routine situations; may be unusually alert or underestimating sleepiness | Healthy adults without sleep disorders; elite athletes; some shift workers after adaptation |
| 6-10 | Higher Normal Daytime Sleepiness | Normal range (mean 4.6, SD 2.8 in healthy Australians without chronic sleep disorders). Zero to 10 represents the 2.5-97.5th percentile. | General population reference range. Most adults without sleep disorders score in this band. |
| 11-12 | Mild Excessive Daytime Sleepiness (EDS) | Mild hypersomnolence; may be noticeable in high-somnificity situations (passive activities) | Mild OSA (AHI 5-15), early narcolepsy, sleep restriction (chronic insufficient sleep) |
| 13-15 | Moderate Excessive Daytime Sleepiness (EDS) | Clearly abnormal; dozing occurs even in moderately engaging activities (watching TV, reading) | Moderate-severe OSA (AHI 15-30), narcolepsy (some), idiopathic hypersomnia, severe sleep restriction |
| 16-24 | Severe Excessive Daytime Sleepiness (EDS) | Profound hypersomnolence; dozing during minimally somnificent activities (driving, talking, eating) | Severe OSA (AHI >30), narcolepsy (typical 16-24), severe idiopathic hypersomnia, Kleine-Levin syndrome (episodic) |
ESS vs Other Sleepiness/Fatigue Scales
| Scale | Construct Measured | Time Frame | Items (n) | Administration | Strengths | Limitations |
|---|---|---|---|---|---|---|
| Epworth Sleepiness Scale (ESS) | Average sleep propensity (dozing tendency) | "In recent times" (weeks to months) | 8 | 2-3 minutes self-report | Widely validated, MCID established (2-3 points), available in many languages, correlates with functional outcomes (driving, work performance) | Subjective, does NOT measure fatigue (only sleepiness), poor correlation with MSLT in some studies, requires literacy |
| Stanford Sleepiness Scale (SSS) | Current subjective drowsiness (momentary) | "Right now" (this minute) | 1 (7-point scale) | 10 seconds | Very quick, captures circadian variation, sensitive to sleep deprivation acutely | Does NOT measure trait sleepiness, fluctuates hour-to-hour, not stable for diagnosis |
| Karolinska Sleepiness Scale (KSS) | Current level of alertness (9-point) | "Right now" (this minute) | 1 (9-point scale) | 10 seconds | Validated for driving simulators, real-time monitoring, sensitive to sleep loss | Momentary only, requires real-time assessment (cannot recall historically) |
| Multiple Sleep Latency Test (MSLT) | Objective sleep propensity (physiologic) | Day of testing (4-5 nap opportunities) | N/A (polysomnography-based) | Full day in sleep lab | Objective (no reporting bias), gold standard for narcolepsy (SOREMPs), used for legal/disability | Expensive, time-consuming, poor correlation with subjective sleepiness in some populations, one-day snapshot |
| Maintenance of Wakefulness Test (MWT) | Ability to stay awake (objective) | Day of testing (4 trials) | N/A (polysomnography-based) | Full day in sleep lab | Objective, better for treatment response (CPAP, stimulants), used for driving/occupational assessment | Expensive, ceiling effects in normal individuals, not diagnostic for narcolepsy |
| Fatigue Severity Scale (FSS) | Fatigue (weariness, exhaustion) | "Past week" | 9 | 5-10 minutes | Standard for fatigue in MS, Parkinson's, post-viral syndromes | Confounded with depression, does NOT measure sleepiness (overlaps but distinct construct) |
| PROMIS Sleep Disturbance | Sleep quality and disturbances | "Past 7 days" | 8a short form (6-8 items) | 5 minutes | Computer adaptive testing available, NIH-funded, good for research | Less specific for sleepiness vs sleep quality |
How it Works
The Eight ESS Questions (1997 Standard Version)
1. Sitting and reading
2. Watching TV
3. Sitting, inactive in a public place (e.g., a theater or a meeting)
4. As a passenger in a car for an hour without a break
5. Lying down to rest in the afternoon when circumstances permit
6. Sitting and talking to someone
7. Sitting quietly after a lunch without alcohol
8. In a car, while stopped for a few minutes in traffic
Scoring Method
For each of the 8 situations, the patient rates their usual chance of dozing off or falling asleep (not just feeling tired):
• 0 = No chance of dozing
• 1 = Slight chance of dozing
• 2 = Moderate chance of dozing
• 3 = High chance of dozing
Total ESS Score = Sum of all 8 items (range 0-24)
Rules:
• Scores must be integers (0-3 per item). If patient reports half-values (e.g., 1.5), take at face value, sum, then round total up if includes half.
• If ANY item is missing, the total is INVALID (cannot interpolate). The 1997 version added instruction "It is important that you answer each question as best you can" to reduce missing responses (<1% invalid now).
• Do NOT provide score interpretation before administration (may bias responses).
Recall Period and Versions
The standard ESS uses an open recall period: "in recent times" (intended to mean the past few weeks to months, not days). This captures stable trait sleepiness. Version history: 1990 original (no specific instruction, 5% missing data), 1997 revision (added "It is important that you answer each question as best you can", missing data <1%). This 1997 version is the current standard. For clinical trials monitoring treatment response (e.g., CPAP for OSA), a modified version specifying "over the last month" may be used with permission from the copyright holder (Mapi Research Trust).
Minimum Clinically Important Difference (MCID)
MCID in Obstructive Sleep Apnea (Patel et al. 2018, n=99 CPAP-treated patients): The minimum clinically important improvement in ESS is between -2 and -3 points. Distribution-based methods: 0.5 × SD = 2.65, SEM = 2.21. Anchor-based methods: patients reporting "little less sleepy" had mean change -2.5 (2.1). ROC analysis: ESS change of -2 points had AUC 0.93 (sensitivity 91%, specificity 88%) for identifying patients who felt at least "little less sleepy". A change of -3 points had sensitivity 80%, specificity 88%. Clinical application: In OSA patients treated with CPAP, a decrease of 2-3 points is clinically meaningful (not just statistically significant). A patient improving by ≥2 points is likely to perceive real benefit in daytime sleepiness.
Clinical Pearls
Critical Pearl #1: ESS Measures Sleepiness, Not Fatigue
The ESS specifically asks about "dozing off or falling asleep" — not feeling tired, weary, exhausted, or lacking energy. Patients frequently confuse fatigue (low energy, weariness from exertion) with sleepiness (physiologic drive to sleep). A patient who says "I'm exhausted all the time but never actually fall asleep during the day" has fatigue, not hypersomnolence, and will score low on ESS. Conversely, a patient with severe sleepiness may score high despite denying "fatigue." Use the ESS to distinguish: "In these situations, do you actually fall asleep, or just feel tired?" This distinction guides differential diagnosis: Fatigue without sleepiness suggests depression, chronic fatigue syndrome, fibromyalgia, or medical illness (anemia, hypothyroidism, heart failure). Sleepiness without fatigue suggests OSA, narcolepsy, idiopathic hypersomnia, or insufficient sleep syndrome.
Critical Pearl #2: Normal Range is 0-10 (Not 2-10)
The 1991 publication reported "normal range 2-10," but subsequent data (Johns & Hocking 2004) in 196 Australian adults without chronic sleep disorders showed mean ESS = 4.6 (SD 2.8), range 0-10. The 2.5th to 97.5th percentile is 0-10. Thus, ESS 0-10 is normal. An ESS of 0 is not "too low" — some alert individuals rarely or never doze. Do NOT raise suspicion because a patient scores 0-5; they may simply be very alert or underestimating (though both are possible). Clinical correlation: If a patient with severe OSA claims ESS = 0, suspect denial or poor insight (some patients do not recognize their sleepiness).
Critical Pearl #3: MCID of 2-3 Points Guides Treatment Response
In CPAP-treated OSA, a reduction of 2-3 points in ESS is the minimum needed for patients to feel "a little less sleepy" (Patel 2018). A change of 1 point, even if statistically significant (p<0.05) in a large trial, is NOT clinically meaningful to patients. For clinical practice: (1) When initiating CPAP, tell patients: "A decrease of 2-3 points on the ESS is the threshold for you to notice improvement." (2) After 3 months of CPAP, a patient with baseline ESS 14 who improves to 11 (Δ -3) has achieved MCID; one who improves to 13 (Δ -1) has not. (3) If no MCID achieved despite good CPAP adherence (>4 hrs/night), consider: inadequate pressure, residual leaks, comorbid insomnia (COMISA), or alternative diagnosis (narcolepsy, PLMD, depression).
Critical Pearl #4: The "High Somnificity" Items (5 and 6)
Not all items are equal. Item 5 ("lying down to rest in the afternoon") has the highest somnificity — most people, even healthy individuals, will sometimes doze in this situation. Item 6 ("sitting and talking to someone") has the lowest somnificity — dozing here is highly abnormal and suggests severe hypersomnolence. In Rasch analysis, the items form an ordinal hierarchy of "difficulty" (ease of falling asleep): Item 5 (easiest) → Items 1,2,3,7,8 (intermediate) → Item 4 → Item 6 (hardest). A patient who endorses "high chance of dozing" (score 3) on Item 6 is extremely sleepy (ESS often >16) and should raise suspicion for narcolepsy or severe OSA, even if total score is not extremely high.
Common Pitfalls and Biases
Recall bias and poor insight – Patients with OSA often underestimate their sleepiness ("I never fall asleep during the day") despite objective evidence (MSLT showing short sleep latencies). This is especially common in men, older patients, and those who live alone (no one to report observed dozing). Corroborative history from bed partner (observed apneas, choking, dozing while driving) is essential.
Confounding by caffeine, nicotine, or medications – Patients who consume high-dose caffeine (coffee, energy drinks, prescription stimulants) may have artificially low ESS scores despite underlying sleepiness. Similarly, sedating medications (antihistamines, benzodiazepines, gabapentin, opioids, muscle relaxants, some antidepressants) increase ESS scores and may mimic hypersomnolence of sleep disorders. Ask about all substances: "How much coffee/tea/soda do you drink daily? Any energy drinks? Any prescribed or over-the-counter sedatives?"
Depression and the "fatigue" confound – Major depression frequently presents with fatigue (low energy, anergia) but not necessarily sleepiness (dozing). The ESS may be normal (0-10) in depressed patients who report severe "tiredness." Conversely, some depressed patients have hypersomnia (increased sleep quantity, difficulty waking) and may have elevated ESS. Use PHQ-9 or other depression screen to disentangle.
Circadian disorders – In delayed sleep phase syndrome (DSPS) or shift work disorder, the ESS may be normal when measured in the afternoon (patient's biological night) but severe when measured in the morning (patient's biological day). Standardize ESS administration time (mid-afternoon, 2-4 PM) for consistent results.
Low sensitivity in mild OSA – ESS has poor sensitivity for mild OSA (AHI 5-15). Many patients with mild OSA have normal ESS (0-10) but still benefit from CPAP (improvements in quality of life, blood pressure, cognitive function). Do NOT rely on ESS alone to decide CPAP candidacy; use STOP-BANG or Berlin questionnaire for screening, and objective testing (home sleep apnea test or polysomnography) for diagnosis.
Poor correlation with Multiple Sleep Latency Test (MSLT) – The ESS and MSLT measure related but distinct constructs. The ESS asks about 'usual chances' of dozing over weeks; the MSLT measures physiologic sleep propensity on a single day in a darkened room. Correlations are weak to moderate (r = 0.3-0.5). A patient can have a normal ESS but pathologic MSLT (e.g., early narcolepsy with preserved insight) or elevated ESS but normal MSLT (e.g., anxiety, psychophysiologic insomnia). Do NOT substitute ESS for MSLT when MSLT is clinically indicated (suspected narcolepsy, hypersomnia with long sleep time).
Legal misuse for driving decisions – The official ESS website warns: "The ESS should not be used in isolation in circumstances where the scores could determine outcomes with potential legal implications, such as granting or withholding a driver's license." Very high scores (>15) correlate with increased drowsy driving crashes, but a single ESS cannot determine an individual's risk at a specific time. For commercial drivers, follow DOT regulations (require sleep study for ESS >10 in high-risk populations).
ESS in Special Populations
| Population | ESS Performance | Specific Considerations | Alternative Tools |
|---|---|---|---|
| Elderly (≥65 years) | ESS scores slightly lower than younger adults (age-related sleep depth reduction, more napping reduces pressure) | Normal range may shift down (0-8). CPAP improves ESS but effect size smaller than in younger patients (PREDICT trial: mean Δ -2.0 vs -4.5 in younger) | ESS still valid; consider objective testing (home sleep test) if ESS normal but clinical suspicion of OSA high (snoring, witnessed apneas, hypertension) |
| Pregnancy (3rd trimester) | ESS often elevated (physiologic sleep fragmentation, discomfort, restless legs). Mean ESS 8-10 in 3rd trimester vs 6 in non-pregnant | Distinguish normal pregnancy-related sleepiness from OSA (ESS alone insufficient). OSA in pregnancy associated with preeclampsia, gestational diabetes, fetal growth restriction. | STOP-Bang (modified for pregnancy), Berlin questionnaire, home sleep testing with validated devices |
| Children (6-17 years) | Modified version available (ESS-CHAD, Child and Adolescent). Normative data: mean ESS 4-8, >12 abnormal in most studies | Parent-report version (questions about child's dozing in school, during screen time, as passenger in car). Not validated for preschool children (<6 years) | ESS-CHAD (requires license), Pediatric Daytime Sleepiness Scale (PDSS), actigraphy |
| African American patients | ESS scores systematically higher (1-3 points) than Caucasian Americans even when matched for OSA severity, BMI, socioeconomic status | Reason unclear (may reflect cultural differences in reporting, chronic stress, or biologic factors). Do NOT assume higher ESS indicates more severe OSA without objective testing. | Use same thresholds but caution against over-interpreting mild elevations (ESS 11-12 in African American patient may be normal variant). Obtain objective sleep study if clinical suspicion. |
| Chronic Kidney Disease (CKD), not on dialysis | ESS often elevated due to uremia, anemia, peripheral neuropathy (restless legs), sleep fragmentation | Correlates with eGFR (lower eGFR → higher ESS). Improves after kidney transplantation | ESS valid but may remain elevated even after adequate dialysis (residual uremic sleepiness). Evaluate for comorbid OSA (high prevalence in CKD) |
| Heart failure (HFrEF, HFpEF) | ESS often normal or mild elevation; Cheyne-Stokes respiration causes sleep fragmentation but patients often do NOT report sleepiness | Discrepancy between high apnea-hypopnea index (AHI) and low ESS is classic for central sleep apnea (CSR-CSA). Low ESS does NOT rule out sleep-disordered breathing in heart failure. | Home sleep testing with central apnea detection (respiratory effort bands, transcutaneous CO2). Polysomnography preferred. |
Next Steps
Step-by-Step Clinical Actions Based on ESS Score
Linking ESS to Management in OSA (Per AASM Guidelines)
| ESS Category | Likely OSA Severity | First-Line Treatment | Follow-up Plan | When to Refer to Sleep Specialist |
|---|---|---|---|---|
| Normal (0-10) | Variable - may have mild OSA or no OSA | If symptoms (snoring, fatigue) but ESS normal: lifestyle modification (weight loss, positional therapy, avoid alcohol before bed). CPAP shown to improve quality of life even in non-sleepy OSA (CAT, FOSQ) but insurance may not cover without ESS elevation. | Reassess in 3-6 months if symptoms persist. Consider home sleep test if STOP-Bang ≥3 despite normal ESS. | STOP-Bang ≥5 or witnessed apneas + hypertension/atrial fibrillation/heart failure, regardless of ESS |
| Mild EDS (11-12) | Mild-moderate OSA (AHI 5-25) typical | CPAP (first-line) OR oral appliance if CPAP not tolerated (mandibular advancement device). Weight loss (effective but slow). | Repeat ESS 3 months after CPAP initiation. Target ESS reduction of ≥2 points (MCID). Titrate pressure based on residual events (AHI <5 on device data). | Failure of CPAP (adherence <4 hrs/night despite 4 weeks of support), persistent ESS >12 after 3 months of good adherence, or suspected comorbidity (narcolepsy, PLMD). |
| Moderate EDS (13-15) | Moderate-severe OSA (AHI ≥15) very likely | CPAP strongly recommended. Auto-CPAP (APAP) acceptable for uncomplicated OSA. Consider oral appliance only if CPAP refused or intolerant but less effective for severe OSA. | Repeat ESS at 3 and 12 months. Evaluate adherence (download CPAP data at 1, 3, 12 months). Target ESS <10 or reduction ≥4 points (clinically significant). | Same as above + any patient with comorbid insomnia (difficulty falling or staying asleep despite CPAP) - refer for cognitive behavioral therapy for insomnia (CBT-I). |
| Severe EDS (16-24) | Severe OSA (AHI >30) or narcolepsy/idiopathic hypersomnia | CPAP (first-line). If severe OSA with severe EDS, consider short-term modafinil or armodafinil as adjunct for residual sleepiness (after optimizing CPAP). Caution: do NOT use stimulants as monotherapy without treating OSA. | ESS should drop substantially (≥5-8 points) with effective CPAP. If ESS remains >15 after 3 months of optimal CPAP (including adequate pressure, mask fit, adherence >6 hrs/night), strongly consider alternative or additional diagnosis (narcolepsy, idiopathic hypersomnia, depression, sedating medications). | Refer to sleep specialist if: (1) No improvement (ESS remains >15) after 3 months of optimal CPAP, (2) Suspected narcolepsy (cataplexy, sleep paralysis, hypnagogic hallucinations, MSLT needed), (3) Need for stimulant therapy (requires specialist evaluation due to abuse potential and cardiovascular risk). |
Sample Clinical Documentation for CPAP Progress Note
Example Note: "Patient with severe OSA (AHI 45, baseline ESS 18) initiated CPAP 3 months ago with auto-CPAP (5-15 cmH2O). Adherence: downloaded data shows usage 6.2 hrs/night, residual AHI 2.1, mask leak within acceptable range (<24 L/min). Current ESS = 11 (Δ -7 points, exceeding MCID of 2-3 points). Patient reports feeling "much less sleepy" (global rating of change: 2 = moderately less sleepy). Goal ESS <10 achieved. Continue CPAP, repeat ESS in 12 months or sooner if symptoms change."
The Evidence
Primary Source: Minimum Clinically Important Difference (MCID)
The Epworth Sleepiness Scale: Minimum Clinically Important Difference in Obstructive Sleep Apnea
Patel S et al. • American Journal of Respiratory and Critical Care Medicine. 2018;197(7):961-963. doi: 10.1164/rccm.201704-0672LE. PMID: 28961021; PMCID: PMC6020404
View SourceOriginal ESS Development and Validation
A new method for measuring daytime sleepiness: the Epworth sleepiness scale
Johns MW • Sleep. 1991;14(6):540-545. doi: 10.1093/sleep/14.6.540. PMID: 1798888.
Reliability and factor analysis of the Epworth Sleepiness Scale
Johns MW • Sleep. 1992;15(4):376-381. doi: 10.1093/sleep/15.4.376. PMID: 1519015.
Daytime sleepiness and sleep habits of Australian workers
Johns MW et al. • Sleep. 1997;20(10):844-849. PMID: 9415942.
Official ESS Website: Normative Data and Psychometrics
About the ESS - Reference range and interpretation
Johns MW (Epworth Sleepiness Scale Official Website) • epworthsleepinessscale.com. 2024;Accessed via https://epworthsleepinessscale.com/about-the-ess/
View SourceSystematic Reviews and Meta-Analyses
Evaluation of the measurement properties of the Epworth sleepiness scale: a systematic review
Kendzerska TB et al. • Sleep Medicine Reviews. 2014;18(4):321-331. doi: 10.1016/j.smrv.2013.08.002. PMID: 24135493.
Psychometric properties of the Epworth Sleepiness Scale in patients with obstructive sleep apnea: A systematic review and meta-analysis
Wang RC et al. • Journal of Clinical Sleep Medicine. 2022;18(1):255-267. doi: 10.5664/jcsm.9562.
ESS vs MSLT: Poor Correlation Evidence
Comparison of the results of the Epworth Sleepiness Scale and the Multiple Sleep Latency Test
Chervin RD et al. • Journal of Psychosomatic Research. 1997;42(2):145-155. doi: 10.1016/s0022-3999(96)00281-x. PMID: 9076640.
Comparing the Epworth Sleepiness Scale and the Multiple Sleep Latency Test in patients with narcolepsy
Fong SY et al. • Journal of Clinical Sleep Medicine. 2020;16(4):589-595. doi: 10.5664/jcsm.8224.
Origins & History
Dr. Murray W. Johns and the Epworth Hospital
The Epworth Sleepiness Scale was developed by Dr. Murray W. Johns, an Australian sleep physician and researcher, in 1990 at the Epworth Sleep Centre, Epworth Hospital in Melbourne, Australia. Dr. Johns established the sleep center in 1988 and needed a practical, self-administered tool to assess daytime sleepiness in his patients. He named the scale after the hospital where he practiced. The initial version (1990) had eight questions but lacked specific instructions, leading to 5% missing responses. In 1997, he revised the instructions, adding "It is important that you answer each question as best you can," which reduced missing data to <1%. The 1997 version remains the standard for adults. Dr. Johns published the original validation in the journal *Sleep* (1991), reporting internal consistency (alpha 0.88) and test-retest reliability (r=0.82). Over 3,000 peer-reviewed articles have since cited the original work. The ESS is now available in more than 60 languages through Mapi Research Trust, which manages licensing (a license is required for use, though fees may be waived for non-commercial research). Dr. Johns passed away in 2022, but his scale remains the most widely used measure of subjective daytime sleepiness worldwide.
Key Contributors and Timeline
| Year | Contributor(s) | Institution | Contribution |
|---|---|---|---|
| 1990 (developed) | Johns MW | Epworth Sleep Centre, Epworth Hospital, Melbourne, Australia | Creation of the 8-item ESS with 0-3 response scale. Initial clinical use in sleep practice. |
| 1991 (published) | Johns MW | Epworth Hospital, Melbourne | Original *Sleep* publication: n=30 controls, 54 OSA, 20 narcolepsy. Demonstrated discriminant validity (controls mean 5.9, narcolepsy mean 17.5). |
| 1992 | Johns MW | Epworth Hospital | Reliability and factor analysis (*Sleep*). Cronbach's alpha 0.88, one dominant factor (eigenvalue 3.6). |
| 1997 (revision) | Johns MW | Epworth Hospital | Modified instructions to reduce missing data: added "It is important that you answer each question as best you can." This is now the standard version. |
| 1998-2000 | Parkes JD, Johns MW, et al. | Multiple centers (UK, Australia) | ESS validation in narcolepsy: sensitivity and specificity >90% for differentiating narcolepsy from normal controls at ESS >15. Established ESS as screening tool for narcolepsy. |
| 2004 | Johns MW, Hocking B | Epworth Hospital | Revised normal range: n=196 healthy Australians without chronic sleep disorders. Mean ESS 4.6 (SD 2.8, range 0-10). Corrected earlier statement that "normal range 2-10" to "0-10." |
| 2014 | Kendzerska TB, et al. (systematic review) | University of Toronto, Canada | Comprehensive review of 56 studies confirming ESS reliability (ICC 0.81-0.93), internal consistency (alpha 0.73-0.90), and responsiveness to CPAP (SRM >0.8). |
| 2018 | Patel S, Kon SSC, Man WDC, et al. | Royal Brompton Hospital, London, UK / NIHR | Determined MCID of ESS in OSA: -2 to -3 points. Used anchor-based and distribution-based methods (n=99 CPAP-treated patients). Published in *AJRCCM*. |
Licensing and Translations
The ESS is a copyrighted instrument owned by Dr. Johns' estate and managed by Mapi Research Trust (Lyon, France, and Boston, MA, USA). A license is required for any use, including clinical practice (purchase of printed questionnaires), research, electronic implementation, and translation. However, non-commercial academic research may qualify for a fee waiver. Authorized translations exist in over 60 languages, including Spanish, French, German, Mandarin, Japanese, Arabic, Hindi, and many others. Unauthorized modifications (changing wording, response scales, or recall periods) are prohibited by copyright. For clinical trials requiring a specific recall period (e.g., "over the last month"), a modified version may be available with permission. The official website (epworthsleepinessscale.com) provides sample copies, scoring instructions, and licensing information. Researchers should contact Mapi Research Trust for permission before using the ESS in any publication.
Last Comprehensive Review: 2026-07-17