abrupt or progressive (over years). Severity is highest when onset is abrupt in children,
and then decreases with age or with treatment, so that symptoms such as cataplexy can oc-
casionally disappear. Abrupt onset in young, prepubescent children can be associated
with obesity and premature puberty, a phenotype more frequently observed since 2009. In
adolescents, onset is more difficu lt to pinpoint. Onset in adults is often unclear, with some
individuals reporting having ha d excessive sleepiness since bi rth. Once the disorder has
manifested, the course is persistent and lifelong.
In 90% of cases, the first symptom to manife st is sleepiness or in creased sleep, followed
by cataplexy (within 1 year in 50% of cases, within 3 years in 85%). Sleepiness, hypnagogic
hallucinations, vivid dreaming , and REM sleep behavior disorder (excessive movements
during REM sleep) are early symptoms. Excessiv e sleep rapidly progresses to an inability
to stay awake during the day, and to maintain  good sleep at night, without a clear increase
in total 24-hour sleep needs. In the first months, cataplexy may be atypical, especially in
children. Sleep paralysis usually develops ar ound puberty in child ren with prepubertal
onset. Exacerbations of symptoms suggest la ck of compliance with medications or devel-
opment of a concurrent sleep disorder, notably sleep apnea.
Young children and adolescents with narcolepsy often develop a ggression or behav-
ioral problems secondary to sleepiness and/ or nighttime sleep disruption. Workload and
social pressure increase thro ugh high school and college, reducing available sleep time at
night. Pregnancy does not seem  to modify symptoms consisten tly. After retirement, indi-