The standard clinical test for daytime sleepiness used by sleep specialists worldwide. Rate how likely you are to doze off in 8 everyday situations. Takes under 2 minutes.
The Epworth Sleepiness Scale (ESS) was developed by Dr. Murray Johns at Epworth Hospital in Melbourne, Australia, and first published in 1991. It has since been validated in dozens of languages and is used in virtually every sleep clinic worldwide as a standard first-line assessment of daytime sleepiness. Its 8 questions were selected through systematic validation to represent a range of sedentary situations with varying sleep-promoting potential.
The ESS measures trait sleepiness — a person's general tendency to fall asleep in everyday situations, reflecting their average sleep propensity over recent weeks. It does not measure acute sleepiness (how sleepy you feel right now), sleep quality, or sleep architecture. It's a screening tool for excessive daytime sleepiness (EDS), not a diagnostic instrument. A high ESS score indicates that clinical evaluation is warranted, not that a specific diagnosis has been made.
The ESS is distinct from other fatigue measures. Fatigue (tiredness, lack of energy) can exist without sleepiness. The ESS specifically targets the tendency to actually fall asleep — which reflects a physiological sleep drive rather than general tiredness. Many people with depression or chronic fatigue report high fatigue but normal ESS scores. People with sleep apnea typically have elevated ESS scores because their condition prevents restorative sleep and accumulates sleep debt.
Population norms for the ESS: the average score in healthy adults without sleep disorders is approximately 5–6. Scores above 10 are statistically unusual in the general population and warrant clinical attention. In patients referred to sleep clinics, average ESS scores are typically 11–14. Patients with severe obstructive sleep apnea often score 14–18. Narcolepsy patients typically score 16–20. The ESS has been validated against objective sleepiness measures (Multiple Sleep Latency Test) with reasonable correlation, though individual variation is significant.
An ESS score above 10 — particularly if combined with symptoms of snoring, breathing pauses during sleep, morning headaches, or obesity — strongly suggests evaluation for obstructive sleep apnea. Our Sleep Apnea Risk Calculator uses the validated STOP-BANG tool and provides a complementary assessment. A score above 10 combined with sudden uncontrollable sleep attacks, cataplexy (sudden muscle weakness triggered by emotion), or sleep paralysis suggests narcolepsy evaluation. In all cases, an ESS above 10 warrants discussion with a healthcare provider, particularly if the sleepiness is impairing driving, work, or daily function.