Abstract
Excessive sleepiness is a common problem, defined by a complaint of excessive daytime sleepiness almost daily with an inability to stay awake and alert dosing periods at sleep, with episodes of irresistible sleep need or drowsiness or non-intentional sleep, or by a night's sleep time overly extended often associated with sleep inertia. This sleepiness is variable in terms of phenotype and severity to be specified by the out-patient clinic. It is considered to be chronic beyond three months and often responsible for significant functional impairment of school and professional performance, of the accidents and cardiovascular risk. We need to decipher the causes of excessive sleepiness: sleep deprivation, toxic and iatrogenic, psychiatric disorders (including depression), non-psychiatric medical problems (obesity, neurological pathologies...), sleep disorders (as for example the sleep apnea syndrome), and finally the central hypersomnias namely narcolepsy type 1 and 2, idiopathic hypersomnia, and Kleine-Levin syndrome. If careful questioning often towards one of these etiologies, need most of the time a paraclinical balance with a sleep recording to confirm the diagnosis. Patients affected with potential central hypersomnia must be referred to the Sleep Study Centers that have the skills and the appropriate means to achieve this balance sheet.