Daytime Sleepiness (ESS)

What the ESS measures

Developed by Dr. Murray Johns at the Epworth Hospital in Melbourne, the ESS is the world standard method for determining a patient's level of daytime sleepiness. Crucially, it does not ask if a patient feels "tired" or "fatigued"—words that are highly subjective. Instead, it measures "sleep propensity": the quantifiable probability that the subject will actually doze off in specific, standardized, sedentary situations.

The dimensions it assesses

• Obstructive Sleep Apnea (OSA)
• Narcolepsy
• Idiopathic Hypersomnia
• Severe Sleep Deprivation

What to do with your result

1. The "Traffic" Flag (Q8): If a user scores greater than 0 on Question 8 ("In a car, while stopped..."), issue an immediate occupational health warning. Falling asleep at the wheel implies a dangerous loss of autonomous control.
2. Medical Assessment Pathway: If the score is >10, the primary recommendation is not "get more sleep," but rather "schedule a polysomnography (sleep study)." Sleep apnea destroys sleep architecture; sleeping 10 hours with untreated apnea will still result in severe daytime exhaustion.
3. Sleep Hygiene Basics: If the score is borderline (9-11), implement strict CBT-I (Cognitive Behavioral Therapy for Insomnia) protocols: no screens 1 hour before bed, rigid wake-up times, and keeping the bedroom at 65°F (18°C).

Common questions about the ESS

What does the ESS measure?

Measurement of daytime sleepiness and the subject's propensity to fall asleep during routine activities.

Can the ESS diagnose me?

No. Daytime Sleepiness (ESS) is a screening questionnaire, not a diagnostic tool. It can flag that something may need a closer look. It cannot tell you what is causing it. Grief, burnout, a thyroid problem, medication side effects, chronic pain and months of bad sleep are not among its questions, and any of them can move a score. Telling those apart is what a professional assessment is for.

Is this ESS test really free?

Yes. No account, no email address, no payment. Psychometrics Today is funded by donations rather than advertising, which is also what allows us to publish instruments whose authors permit free but non-commercial use.

Are my answers stored or shared?

No. Your answers are scored inside your browser and never sent to us. There is no database of responses, because we never receive any. Closing the tab erases them, which is why results cannot be recovered afterwards.

How often should I retake the ESS?

Most of these questionnaires ask about the past one to two weeks, so retaking sooner than that mostly measures the same period twice. Every two to four weeks is a reasonable rhythm if you are tracking change. A direction of travel over several weeks tells a doctor far more than any single score.

How accurate is the ESS?

Screening questionnaires are good at flagging that something merits attention and poor at establishing what it is. This one is sensitive to how you feel on the day you take it, and many instruments were validated on narrow populations whose cut-offs may not transfer cleanly to everyone. The references at the foot of this page are the primary sources.

Why can I not take the ESS here?

Licensed; commercial use carries a fee. We will not reproduce a questionnaire we have no right to reproduce, so this page explains what it measures instead. The Stanford Sleepiness Scale is free to use.