Narcolepsy and excessive daytime sleepiness

A structured sleep history is the key to the assessment of daytime sleepiness. The Epworth sleepiness scale provides a useful measure of daytime sleepiness. Assessment in a sleep laboratory is often helpful in finding the cause of excessive daytime sleepiness. Hypocretin-1 and hypocretin-2 are recently described neurotransmitters that help to regulate the sleep-wake cycle; their levels in the brain are reduced in narcolepsy with cataplexy. Moderately effective treatments are available for daytime sleepiness and cataplexy. Approaches to the diagnosis and treatment of narcolepsy are likely to change rapidly over the next few years.