This is an integer value with range from 0-24. The Epworth Sleepiness Scale assesses the daytime sleepiness of patients. Dr Murray W Johns owns the copyright in the ESS (Copyright © M.W.Johns 1990-1997). The official website is http://epworthsleepinessscale.com/. Algorithm: The ESS is computed by adding ALL 8 ITEMS (SLEA12A TO SLEA12H). If any item is missing then ESS is missing. Warning: The levels of each item need to be recoded as follows: No chance (from 1 to 0), slight chance (from 2 to 1), moderate chance (from 3 to 2) and high chance (from 4 to 3).