The Epworth Sleepiness Scale, otherwise known as the ESS is a self-administered assessment consisting of 8 questions. The questionnaire asks respondents to rate their chances of falling asleep or dozing off while participating in eight different activities, on a 4-point scale of 0 to 3. The activities mentioned are usually engaged in by most people daily, or at least weekly. The final score can range from 0 to 24, being the summation of all 8 questions. Higher scores indicate a higher average sleep propensity (ASP) in a person’s daily life, which is essentially their daytime sleepiness. The normal range for ASP in healthy adults should be between 0 – 10, so any score higher than that could indicate a need for further screening.

Below is an example of how this assessment is usually presented in clinical settings.



The ESS questionnaire is available in multiple different languages and takes no more than 2-3 minutes to complete. It is also currently the only available assessment for scoring ASP directly. Since it’s development in 1990, there have been copious studies and research to support the validity of the assessment in identifying potential sleep disorders.



Because the ESS is self reported, it is at risk for the inevitable response biases and other sources of inaccuracy that would be found in other self – reported assessments. This is why the ESS should not be used alone, especially in cases where scores could have legal implications, like withholding a driver’s license due to excessive daytime sleepiness. 

The ESS cannot be used as a diagnostic tool alone and is not useful in assessing a person’s sleep habits, and it is not suited for people with serious cognitive impairments or individuals who face rapid changes in sleep patterns over time. 


Overall Reliability?

Although the ESS is not meant to be a diagnostic tool for directly identifying a sleep disorder, it has proven to be very useful and simple as a screening assessment to help physicians determine if there could be a need for further testing. It is most successful when administered by a physician, and higher scores could indicate sleep disorders, such as hypersomnia, sleep apnea, and narcolepsy upon further testing.


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