Parasomnia Part II
Risk Factors: One study found that arousal parasomnias were associated with sleep apnoea, alcohol intake at bedtime, mental disorders, shiftwork, excessive need for sleep, and stress.
Nightmare Dissorder: This is synonymous with dream-anxiety attacks. Bad dreams/nightmares occur in REM sleep, with associated severe anxiety and symptoms of increased sympathetic outflow. There is complete alertness and recall of dreams on waking.The presence and recollection of the dream is what helps to differentiate this condition from night terrors. Sufferers may have experienced previous trauma that is relived. This presentation is a major symptom of post-traumatic stress disorder.
Epidemiology: Prevalence in children aged 3–5 yrs is estimated at 10–50% with an unknown adult prevalence. Up to 50% of adults report occasional nightmares.
Prognosis: Most children outgrow nightmare disorder, but a small proportion may suffer into adulthood, with improvement in later life.
Night Terrors: This is synonymous with sleep terror disorder. Disordered arousal occurs during NREM sleep, causing extreme panic and loud screams/movement. A sudden arousal from non-dreaming sleep occurs, usually about 90 minutes or so after falling asleep. There is often an accompanying scream or shout. There may be symptoms of increased sympathetic outflow. Initially the patient may be unresponsive and tends to be confused, disoriented and unable to recall what has caused them to wake. There may be nonsense or indistinct speech, and bed-wetting. The sufferer may hit/throw objects or leave the bedroom. There is little or no subsequent recall of events.
Epidemiology: DSM-IV estimates prevalence at 1–6% in children although recurrent episodes are less common. Adult prevalence is estimated at <1%. , Night terrors occur most frequently in children aged 3–12, with median age of onset 3.5 yrs.
Prognosis: Virtually all children grow out of night terrors before adolescence. Adult night terrors tend to be more chronic with a waxing and waning course.
Sleep Walking Dissorder: Usually arises during NREM sleep and involves an apparently sleeping or unaware person performing complex, automatic behaviour and various motor functions. Typical activities include walking around the house, wandering outside, carriage of possessions and ‘looking’ in cupboards or doorways. There is a large degree of variation in the activities performed. This can range from someone who merely sits up in bed to a wandering or rambling journey around the house, or even outside it. Complex tasks such as eating, work-related activities or sexual behaviour may be performed, and the patient may talk. Patients usually awake confused and amnestic for any of their activity. It usually occurs during NREM (non-dreaming) sleep and can be worsened or precipitated by sleep deprivation. The patient may wake, or simply go back to sleep in their bed or somewhere else, without coming to until the morning.
Epidemiology: Recurrent sleepwalking affects about 5% of children but episodes of the phenomenon may affect up to 30% of children and 7% of adults.
Prognosis: Most children with sleepwalking disorder grow out of it. Adult sleepwalkers tend to have more protracted waxing and waning phases of the phenomenon.
REM Sleep Behaviour Dissorder: This is enactment of the experience of dreams during REM sleep. Kicking, punching, flailing limbs, grabbing, shouting, talking and sitting-up are typical behaviours. It may occur acutely in those withdrawing from alcohol or other sedatives, or chronically when it tends to be the patient’s family or bed partner that brings the problem to medical attention. It may present because of injury to the sufferer or their bed partner. If the patient wakes then this occurs quickly and they are usually immediately lucid and oriented, with complete recall of the dream and subsequent normal behaviour. It is rare for it to cause excessive daytime somnolence. It is often associated with neurodegenerative disorders.
Epidemiology: Thought to be quite rare but likely to be underdiagnosed due to symptoms being attributed to other parasomnias. There may be an increased incidence in some families with autosomal dominant inheritance. Commonest in sixth and seventh decades of life. It is relatively common in the context of those referred to sleep clinics. Telephone survey has found a prevalence of violent behaviour during sleep of about 2%. Probably about a quarter of these were due to the condition, giving a rough population prevalence of ~ 0.5%.
Prognosis: This depends on the underlying associated condition. In patients in whom there is no underlying disorder, the symptoms are frequently amenable to medication.
Restless Leg Syndrome (RLS) and Periodic Limb Movement Dissorder (PLMD): These two conditions may co-exist. RLS tends to cause insomnia due to a constant, involuntary irritation of the legs causing their movement, on retiring to bed. PLMD causes temporally-periodic, sleep-disturbing limb-movements that rarely completely wake the sufferer, but may cause them to feel excessively sleepy during the next day, due to disturbance of the sleep cycle. The majority of patients with RLS will also have PLMD, but only a minority of those with PLMD also have RLS.
Epidemiology: Prevalence of RLS could be as high as 10–20% in the older age group and it is increasingly common with age. It appears to be about twice as common in older women than older men.6,7 PLMD has an estimated prevalence of 4–11% in the elderly, but some estimate it may affect up to 40% of those aged >65 yrs.
There are no specific physical signs of any of these conditions. Mental state examination should be predominantly normal. Significant abnormalities in mental state suggest a psychiatric condition causing a secondary parasomnia. REM sleep behaviour disorder patients (or their bed partners) may show signs of injury.