Sleepiness assessment

Sleepiness is a subjective sensation closely related to the inner desire to sleep, thus intrinsically connected to the underlying processes of sleep regulation. Sleepiness has multifaceted dimensions and should be carefully assessed in the context of an accurate anamnesis to distinguish physiological from pathological (excessive daytime sleepiness) conditions. Several tools are available to measure state and trait subjective sleepiness, as well as to objectively document sleep propensity or alertness. Among validated measures, the Epworth sleepiness scale (ESS) is a useful screening questionnaire, the Multiple Sleep Latency Test (MSLT) is a diagnostic tool for the differential diagnosis of the hypersomnias of central origin, and the Maintenance of Wakefulness Test (MWT) can measure alertness in individuals at risk for sleepiness-related accidents. Other physiological and performance assessment tools are available, including driving simulators, but still require further standardization and validation and can be therefore actually used only for research purposes. The ideal sleepiness assessment tool would have a high face validity toward the real situations in which subjects are at increased risk because of sleepiness.