Night Terrors and Parasomnias

Synonyms: Night terrors=sleep terror disorder=pavus nocturnus;
Nightmare disorder=dream-anxiety attacks;
Sleepwalking disorder=somnabulism (syndrome);
Ekbom's syndrome=restless legs syndrome.

Parasomnias may be defined as undesirable disorders of behaviour or experience that occur during sleep or its specific stages, or during sleep-wake transitions.
Common behavioural problems include unwelcome verbal outbursts or movements.

• Primary parasomnias arise without an underlying physical cause and may be classified by the stage of sleep in which they occur, as REM, Non-REM (NREM) or miscellaneous (no specific stage affected). They are also classified diagnostically on the basis of their characteristic presentation.
• Secondary parasomnias are disorders caused by accompanying physical/psychiatric disturbance leading to sleep-related symptoms, eg seizures, cardiac dysrhythmia or dysfunction, respiratory dysfunction and gastro-oesophageal reflux.

Dyssomnias such as insomnia, in contrast, are disorders of the initiation, timing, quality, maintenance or phasing of sleep, and are not usually associated with aberrant behaviour or experiences.

A Turkish survey of pre-adolescent school-aged children found a 14.4% prevalence of parasomnias. About 1 in 6 children had at least one parasomnia. Bruxism, nocturnal enuresis (considered by some to be a parasomnia) and night terrors were the most common types.²

• Nightmare disorder 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.
• Night terrors DSM-IV estimates prevalence at 1–6% in children although recurrent episodes are less common. Adult prevalence is estimated at <1%.^{1 3} Night terrors occur most frequently in children aged 3–12, with median age of onset 3.5 yrs.³
• Sleepwalking disorder Recurrent sleepwalking affects about 5% of children but episodes of the phenomenon may affect up to 30% of children and 7% of adults.
• REM-sleep behaviour disorder 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%.
• RLS/PLMD 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.^{4 5} 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.^{1 5}

Symptoms

• Nightmare disorder There is a history of a frightening dream/nightmare with associated general arousal. 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.
• Night terrors 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.
• Sleepwalking disorder 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.
• REM sleep behaviour disorder There is acting out of dreams occurring during REM sleep, which is its characteristic feature. 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. An acute presentation suggests alcohol or sedative drug withdrawal or reaction to medication (particularly anticholinergics). It is rare for it to cause excessive daytime somnolence.
• RLS/PLMD The patient's legs feel uncomfortable in a difficult-to-describe way. Adjectives such as pulling, searing, crawling, creeping, and boring may be used to try and convey the sensation.¹ This tends to start shortly after going to bed or at other times of inactivity. Moving the legs, rubbing them, walking about or having a shower/bath may temporarily relieve the sensation. Patients tend to complain to their doctors of the insomnia that this is causing them, which can be severe enough to lead to depression and suicide. PLMD tends to occur once the patient has fallen asleep. There is commonly a rhythmic flexion of the great toe and ankle with partial flexion of the knee/hip. The upper limbs are less commonly affected. The patient's bed partner may present on their behalf, or it can cause sufferers to experience excessive daytime somnolence. They are usually disorders of older patients, but children, particularly those with hyperactivity attention deficit disorder-type behaviour are sometimes affected. Pregnant women appear to be more likely to be affected,⁶ and the condition can vary with the menstrual cycle in some women. Both conditions appear to affect people who suffer from peripheral neuropathy, postpolio syndrome, spinal cord pathology, myelitis, renal failure requiring haemodialysis and iron deficiency anaemia.¹

Signs

There are no specific physical signs of any of these conditions. Mental status 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.

• Generalised anxiety disorder
• Panic disorder
• Obstructive sleep apnoea
• Post-traumatic stress disorder
• Undiagnosed or decompensated physical illness, eg heart failure leading to paroxysmal nocturnal dyspnoea, neuropathy/myelopathy causing restless legs
• Undiagnosed/relapsing psychiatric illness
• Epileptiform disorders, especially temporal lobe epilepsy
• Fugue states
• Hypnagogic or hypnopompic phenomena (abnormal experiences associated with falling asleep or waking up)
• Alcohol or other drug misuse/withdrawal

No specific investigations are needed unless there is reason to suspect an underlying physical condition causing a secondary parasomnia, eg EEG/CT/MRI for temporal lobe epilepsy, CXR/echocardiography for suspected heart failure, investigations/referral for suspected obstructive sleep apnoea. In those with RLS/PLMD then an FBC to exclude iron deficiency anaemia is worthwhile. In older patients with RLS/PLMD, or new-onset REM sleep behaviour disorder, screening tests such as U&E, LFTs and TFTs and others may be considered useful to exclude physical diseases common in this age group. Patients with atypical or confusing presentations may benefit from referral to a sleep clinic for polysomnography to reach a definitive diagnosis. PLMD has a characteristic EMG pattern if recorded during sleep episodes.

REM sleep behaviour disorder has been associated with Lewy-body and other dementias, Parkinson's disease,⁷ subarachnoid haemorrhage, ischaemic cerebrovascular disease, olivopontocerebellar degeneration, multiple sclerosis and brain stem neoplasms.¹ RLS /PLMD have been associated with iron-deficiency anaemia, pregnancy/menstruation/menopause, chronic renal failure, hip/knee arthritis, neurological disease, peripheral neuropathy, myelitis, radiculopathies, post-polio syndrome and stimulant medications such as caffeine, antidepressants and dopamine antagonists.¹

• Most parasomnias require no definitive treatment other than explanation, reassurance of the sufferer and their family/bed partner, and an offer to follow things up.
• Information leaflets (see internet section) are a relatively easy and effective way of achieving this.
• Once parents of children with terror disorder have been appropriately informed and reassured, the vast majority can cope with the condition and it will usually resolve.
• Medication or other pharmacological factors should be optimised to help reduce the severity or frequency of attacks of parasomnia.
• Patients with underlying physical or psychiatric disease may benefit from adjustment of their treatment or specialist input to help ameliorate sleep-related symptoms.
• REM sleep behaviour disorder is usually treated with nocturnal benzodiazepines such as clonazepam and tricyclic antidepressants where there is some evidence for their efficacy. Levodopa/carbidopa, gabapentin and clonidine are sometimes used but there is little systematic evidence of benefit. Management in the context of dementia/Parkinson's can be difficult and may require expert elderly medicine/psychogeriatric input.
• In RLS and PLMD, dopaminergic agents (anti-Parkinsonian drugs) are used as first-line agents with anticonvulsants, benzodiazepines and other sedatives and opioids also being employed on occasion.⁸
• Psychological therapies such as relaxation therapy, biofeedback and stress reduction may be employed in place of medication for some parasomnias, but evidence for effectiveness is currently lacking.

• Accidental injury
• Overeating during sleepwalking leading to obesity
• Relationship difficulties
• Forensic consequences of behaviour during sleepwalking, particularly if patient ventures into outside world or displays sexual behaviour

• Most children outgrow nightmare disorder, but a small proportion may suffer into adulthood, with improvement in later life.
• Virtually all children grow out of night terrors before adolescence.
• Adult night terrors tend to be more chronic with a waxing and waning course.
• Most children with sleepwalking disorder grow out of it.
• Adult sleepwalkers tend to have more protracted waxing and waning phases of the phenomenon.
• RLS/PLMD have a highly variable prognosis, dependent on whether it is idiopathic or due to an underlying cause.
• Some patients with RLS/PLMD recover spontaneously or in response to treatment, but there may be relapses.
• Where RLS/PLMD persists, it tends to worsen with age.

Sufferers should avoid precipitants, particularly medications, caffeine, alcohol or sedatives, especially at night. Precautions against physical and potential legal consequences of disturbed nocturnal behaviour should be considered.