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

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Many people have periods of low energy or fatigue, but, during a typical day do you experience excessive sleepiness when it is difficult to fight an uncontrollable urge to fall asleep?