Narcolepsy in childhood

Narcolepsy is characterized by excessive daytime sleepiness and symptoms of disordered control of rapid eye movement (REM) sleep. The boundaries between waking and REM sleep become blurred resulting in REM phenomena in wakefulness and features of wakefulness during sleep. Narcolepsy is not rare, with a prevalence of 25–50/100,000 in Western Europe, however many individuals remain undiagnosed for many years after the onset of symptoms [1]. One third of adults with narcolepsy describe their first symptoms appearing before the age of 15 and there is a clear peak of onset in the teenage years [2]. The classic narcolepsy tetrad comprised excessive daytime sleepiness, cataplexy (loss of muscle tone triggered by strong emotion, most frequently laughter), sleep paralysis and hypnagogic (on falling asleep) and hypnopompic (on waking) hallucinations. Disturbed nighttime sleep was often added to make up a pentad. These symptoms apart from excessive daytime sleep and cataplexy are not uncommon in unaffected individuals and other sleep disorders. The International Classification of Sleep Disorders defines narcolepsy without cataplexy as excessive daytime sleepiness and multiple sleep onset REM periods on multiple sleep latency testing (MSLT) [3]. Narcolepsy with cataplexy is associated with a deficiency of cerebrospinal fluid (CSF) hypocretin, a