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any increased risk of developing neurodegenerative disorders and the underlying mechanisms
for the RBD may be different.

Treatment includes withdrawal of drugs that may contribute and safety precautions, as for
the NREM parasomnias (see above). Even though patients with RBD rarely leave the bed,
there is a risk of falling out of bed if movements are violent. Protecting the bed partner is
important and sometimes sleeping in separate beds is warranted. RBD often responds well to
low doses of clonazepam (0.5–2 mg). Again, there are no randomised controlled trials. More
recently, melatonin has been shown to be an effective treatment of RBD, often in higher
doses, up to 12 or even 15 mg36.

Sleep-wake transition disorders
The most common of these are hypnic or myoclonic jerks that occur on going to sleep or
waking. The jerks are benign in nature and do not require any treatment apart from
reassurance of their harmlessness.

Rhythmic movement disorders are less common sleep wake transition disorders:
1. Occur at wake-sleep transition
2. Many times per night
3. Every night
4. Usually in children or adults with learning disability but can occur in adults of normal
intelligence.

Rhythmic movement disorders are characterised by repetitive movements occurring
immediately prior to sleep onset and can continue into light sleep. The most dramatic type is
head banging (jactatio nocturna) but other movements, such as body rocking, can also be
seen. Movements often start in infancy or childhood and persistence of movements beyond
the age of ten is often associated with learning disability or autism. Movements can however
also continue in adults of normal intelligence. Patients are usually aware of movements. It
has been suggested that it might represent a learnt behaviour and it is often difficult to treat.
Protection of the patient, i.e. padding of bedhead or a helmet, may be required in severe cases.
Benzodiazepines, trycyclic antidepressants or gabapentine can be tried but responses are
usually disappointing.

Periodic limb movements of sleep (PLMS)
1. Occur in the early part of the night/throughout
2. Series of >4 in any sleep stage, up to hundreds per hour
3. Every night
4. Idiopathic form rare under the age of 40 years.

Periodic limb movements of sleep (PLMS) can occur in association with restless leg
syndrome (RLS) or separately. Many people with RLS also have PLMS but the converse is
not true and most people with PLMS do not have RLS. Periodic limb movements often
consist of typical dorsiflexion of toes and ankle but may also affect the knee, hip or arms.
Movements are repetitive, occurring every 5–90 seconds. Movements can occur during all
stages of sleep, including REM sleep. PLMS may occur in up to 50% of people over 50 years
of age and are sometimes associated with daytime movements. The periodic limb movement
index (PLMI) averaging the number of movements per hour may be helpful to ascertain
severity of symptoms. Less than five per hour is likely to be normal in younger people but
this cut-off may be too low a limit in older patients. Movements are only clinically
insignificant if associated with daytime symptoms such as excessive daytime sleepiness
(periodic limb movement disorder – PLMD).