Sleep Disorders 1691 Sleep attacks: sudden onset of sleep even during activities such as meals.
2 Cataplexy: sudden loss of muscle tone, leading to collapse without loss
of consciousness. This is often precipitated by strong emotion such as
anger or amusement.
3 Sleep paralysis: loss of ability to move or speak while awake, either just
before going to sleep, or just after waking up.
4 Hallucinationson falling asleep (hypnagogic hallucinations) or waking
up (hypnopompic hallucinations). These are effectively waking dreams.
These four features occurring together make up the classical narcolepsy
tetrad. It is even commoner to get just one, two or three of these features.
When cataplexy is present, the cause is generally loss of the hypothalamic
neurones that produce hypocretins (also known as orexins). These are
excitatory neuropeptides that play a central role in the regulation of
wakefulness, while also influencing food intake and energy expenditure.
The neuronal loss is probably due to an autoimmune process that is more
likely to occur in genetically predisposed individuals, possibly triggered by
streptococcal or viral infections.
Methylphenidate is often useful for sleep attacks (in combination with
good sleep hygiene and planned naps). Various types of antidepressants –
including tricyclics and selective serotonin or noradrenaline reuptake
inhibitors – can reduce or prevent cataplexy. Sleep paralysis and halluci-
nations can also be helped by antidepressants, though reassurance is often
enough.
Kleine-Levin syndrome
This rare syndrome typically affects adolescent males. It involves episodes
of excessive sleep, overeating and sexually disinhibited behaviour, some-
times accompanied by mood disorder, restlessness and bizarre behaviour.
The episodes can last hours, days or weeks, and recur every few weeks or
months. Hypothalamic abnormalities have been suspected but not proven.
Adolescents and their parents and teachers can be reassured that this is
a recognised condition that is neither wilful nor psychotic. Tricyclics or
lithium may reduce recurrence. It usually remits spontaneously in later
adolescence or early adulthood.
Medication
Education, reassurance and management advice are the main treatments
for sleep disorders in childhood and adolescence. As described above,
there are some indications for medication. However, it is important to
stress that hypnotics should seldom be used. Although effective in the
short term for common problems with getting to sleep or staying asleep,
hypnotics are far less effective (and potentially more hazardous) than
psychological approaches in the long term. It is generally a mistake to use
benzodiazepines for more than a week or two since they lose effectiveness,