Calculated - Total score based on an 8-item questionnaires ranking likelihood of dozing off Johns MW 1991 (PubMed ID: 1798888). Scale 0-3 for individual items; 0 to 24 for overall score.
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).
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