Answer: The Epworth Sleepiness Scale is a self administered short questionnaire used to assess daytime somnolence that results from sleep disorders such as sleep apnea or insomnia.
Sleep disorders are very common conditions that can severely worsen a person's quality of life. Even minor sleep disturbances can lead to a worsening of health outcomes. Poor night time sleep leads to daytime sleepiness, which puts a person at risk for all variety of injuries. People experience poor sleep as a result of sleep apnea or insomnia, for example.
The Epworth Sleepiness Scale (ESS) was developed by Dr. Johns in 1990. The test has since undergone one major revision in 1997, and this is currently the diagnostic test that is used. The test is a self report questionnaire, and it gives a numerical readout of daytime sleepiness.
How the Epworth Sleepiness Scale is scored
The ESS consists of of eight short questions. For each question, the patient is asked to think of "recent times" and evaluate the likelihood that they would fall asleep during said situation. They will rate the probability they will fall asleep on a scale from 0 to 3, with 0 meaning "would never doze" and a 3 meaning "high chance of dozing."
The eight questions on the Epworth sleepiness scale ask the likelihood of dozing during the following activities:
Sitting and reading
Sitting inactive in a public place
As a passenger in a car for an hour without a break
Lying down to rest in the afternoon
Sitting and talking to someone
Sitting quietly after a lunch without alcohol
In a car, stopped for a few minutes in traffic
The points across these eight measures are then totalled. The normal range is defined to be a sum between zero and ten. A score between 11 and 24 indicates that the patient may be experiencing excessive daytime sleepiness.
Shortcomings of the Epworth Sleepiness Scale
Most notably, the ESS is a self report questionnaire. This means that it is subject to respondent bias, where the patient may intentionally deceive the experimenters to achieve some outcome that they desire. For example, they may lie to get lower scores to avoid having to wear a continuous positive airway pressure (CPAP) machine. Alternatively, they may inflate their scores to receive a positive diagnosis of daytime sleepiness, which can allow them to get a prescription for stimulant medications with abuse potential, such as dextroamphetamine.
It is noted that scores on the Epworth sleepiness scale are sensitive to cultural influences. The scale was designed for monophasic sleepers, such as for many people in the United States and the UK. Monophasic sleepers have one long rest period at night, with a prolonged wake period in the day. The test shows bias against cultures with biphasic sleep patterns, such as Mediterranean and southern European countries, as well as Spain and their former colonies. in these countries, people may often take a midday siesta, which can cause their self report scores on the Epworth questionnaire to be higher.