Written and edited by leading clinicians and researchers in sleep medicine, this is the first book to focus on the causes, consequences and treatment of disorders of excessive sleepiness. Extensive coverage is provided for all known causes of sleepiness, including sleep deprivation, obstructive sleep apnea syndrome, narcolepsy and other hypersomnias of central origin, shift work, and medical and psychiatric disorders. Since many causes of sleepiness are difficult to differentiate from each other, and treatment modalities can vary greatly from one disorder to another, this book helps the clinician to formulate a differential diagnosis that will ultimately lead to the correct diagnosis. Epidemiology, evaluation of the sleepy patient, diagnostic investigations including neuroimaging, subjective and objective testing, cognitive effects of sleepiness, motor vehicle driving issues, medico-legal aspects of sleepiness, and therapy are also discussed in detail. This is an essential resource for neurologists, psychiatrists and sleep specialists.