Insomnia and REM Sleep Behaviour Disorder
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Direct answer
Insomnia is persistent difficulty with sleep onset, maintenance or quality that impairs daytime function, and cognitive behavioural therapy for insomnia (CBT-I) is the first-line treatment. REM sleep behaviour disorder is different: it is loss of the normal REM atonia, so patients act out dreams, and it is a prodrome of synucleinopathies such as Parkinson disease and dementia with Lewy bodies.
What you must remember
- Chronic insomnia: difficulty with onset, maintenance or early waking at least three nights a week for three months, with daytime impairment.
- CBT-I: first line, combining sleep restriction, stimulus control, cognitive restructuring and sleep hygiene; its benefits persist after treatment ends.
- Hypnotics: Z-drugs and benzodiazepines are limited to short courses because of dependence, falls and, with zolpidem, complex sleep behaviours.
- Secondary causes: obstructive sleep apnoea, depression, chronic pain, restless legs syndrome, thyroid disease and corticosteroids must be excluded first.
- REM sleep behaviour disorder: loss of REM atonia on polysomnography, with violent dream enactment, typically in men over 50.
- Prodrome: idiopathic RBD often precedes Parkinson disease, dementia with Lewy bodies and multiple system atrophy by years.
- Treatment of RBD: low-dose clonazepam or melatonin, with bedroom safety measures such as removing sharp objects.
- Drugs that worsen RBD: SSRIs, SNRIs and tricyclic antidepressants can precipitate or worsen the disorder and should be reviewed.
Insomnia and RBD compared
The two conditions share the bedroom but differ in mechanism, investigation and prognosis, which is why exams compare them directly.
| Feature | Chronic insomnia | REM sleep behaviour disorder |
|---|---|---|
| Core problem | Difficulty sleeping | Loss of REM atonia |
| Typical patient | Adults, more often women and older people | Men over 50 |
| Key symptom | Long latency, early waking | Dream enactment, shouting, punching |
| Investigation | History, sleep diary, screen for causes | Polysomnography with REM submental EMG |
| Main treatment | CBT-I, then short hypnotics | Clonazepam or melatonin, bedroom safety |
| Neurological link | Often secondary to psychiatric or medical disease | Prodrome of synucleinopathy |
Insomnia is usually diagnosed clinically and managed by addressing its drivers. RBD demands polysomnography and long-term neurological follow-up, because the sleep disorder often predates the motor features of Parkinson disease by years.
In a clinical stem, the first question is whether the patient describes trouble falling asleep or movement during sleep. Patients with RBD often have little memory of their episodes, so a history from the bed partner is more useful than the patient's own account.
Where the exam tries to catch you
Sleep questions reward the candidate who separates a behavioural problem from a neurodegenerative warning sign.
- Trap: prescribing long-term zolpidem for chronic insomnia Correct: CBT-I is first line, and hypnotics are restricted to short courses because of dependence and falls.
- Trap: calling RBD a variant of sleepwalking or night terrors Correct: RBD occurs in REM sleep with dream enactment, whereas sleepwalking and night terrors are NREM parasomnias.
- Trap: treating RBD as a purely psychiatric problem and starting an SSRI Correct: antidepressants can precipitate RBD, and the condition is a neurological prodrome.
- Trap: diagnosing primary insomnia without excluding sleep apnoea Correct: obstructive sleep apnoea and restless legs syndrome must be excluded before labelling insomnia as primary.
Frequently asked questions
How is REM sleep behaviour disorder diagnosed?
REM sleep behaviour disorder is diagnosed by polysomnography showing loss of REM atonia, usually with increased submental and limb muscle activity during REM sleep. A history of dream enactment, sometimes with injury to the bed partner, supports the diagnosis.
What is the first-line treatment for chronic insomnia?
Cognitive behavioural therapy for insomnia is the first-line treatment for chronic insomnia, and its benefits tend to last longer than those of medication. Hypnotics such as zolpidem or benzodiazepines are reserved for short courses to limit dependence and falls.
What treats REM sleep behaviour disorder?
Low-dose clonazepam or melatonin is used to treat REM sleep behaviour disorder, alongside bedroom safety measures such as padding the bed area. Antidepressants that can precipitate the disorder should be reviewed or changed.
Why is REM sleep behaviour disorder linked to Parkinson disease?
Idiopathic REM sleep behaviour disorder is a prodrome of synucleinopathy, including Parkinson disease, dementia with Lewy bodies and multiple system atrophy. Alpha-synuclein pathology affects brainstem circuits that control REM atonia, often years before motor signs appear.
Which secondary causes must be excluded in insomnia?
Secondary causes of insomnia include obstructive sleep apnoea, depression, chronic pain, restless legs syndrome, thyroid disease and drugs such as corticosteroids and stimulants. Excluding these is essential before attributing insomnia to a primary cause.