The majority of sleep disorders result in excessive daytime sleepiness (EDS). ES is measured by sleep clinics using questionnaires to screen patients. These questionnaires ask patients about the symptoms that they’re experiencing. There are many questionnaires and scales available to health care providers. They hope to isolate a particular symptom that can help diagnose a sleep disorder. The Epworth Sleepiness Scale is one of the most prominent. It is considered a standard method of assessment used in the world of sleep medicine.
The Epworth Sleepiness Scale (ESS) is a test for adults developed in 1990 with some modifications to this test being implemented in 1997. The test was developed by Dr. Murray Johns, a private practitioner of Sleep Medicine. He developed ESS so he could assess the daytime sleepiness of his patients. It derived its name from Epworth Hospital in Melbourne, Australia. This is the same hospital where Dr. Johns established the Epworth Sleep Centre in 1988.
What exactly is the ESS?
The ESS is a self-administered questionnaire that has 8 questions that measure the chances of a patient falling asleep while doing activities. There are 8 activities in the questionnaire, one for each question. These activities are those that people often engage in. They don’t have to be daily activities, but they are all at least occasionally done by the patient. This is a questionnaire that takes just 2 to 3 minutes to complete and it is available in multiple languages.
ESS includes scenarios like:
- Sitting and reading
- Watching TV
- Sitting inactive in a public place
- Riding 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 the traffic
How is the ESS scored?
The item-scores in ESS range from 0 to 3. Item-scores should be whole numbers, meaning a patient should not use a .5 score. When a patient uses a half value the one assessing the questionnaire needs to round off the final score to the next whole number. A patient needs to answer all of the items. Not answering even one of the questions will invalidate the entire questionnaire.
The normal range of an ESS score is between 2 and 10. During a test in 2004, adults who have no evidence of a chronic sleep disorder registered a mean ESS score of 4.6. An ESS score between 11-24 represents increasing levels of excessive daytime sleepiness (EDS).
ESS score ranges are as follows:
- 0-5 Lower Normal Daytime Sleepiness
- 6-10 Higher Normal Daytime Sleepiness
- 11-12 Mild Excessive Daytime Sleepiness
- 13-15 Moderate Excessive Daytime Sleepiness
- 16-24 Severe Excessive Daytime Sleepiness
What are the limitations of an ESS?
Just like the other means of measuring sleepiness, ESS item-scores can be subjective. Bias can influence the answers of a patient. That bias can result in an inaccurate score. This is also not an ideal test for patients with cognitive impairment. Any impairment can result in an inaccurate answer and inaccurate results.