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Sleep Disorders
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Succinct notes to superpower your revision
Sleep disorders\: prevalent across medical specialities, including respiratory medicine, general practice, and neurology.
Sleep studies\: crucial for diagnosing sleep disorders\:
Pulse oximetry\: records SpO 2
and pulse rate overnight.
Respiratory polygraphy (rPG)\: measures SpO , pulse, chest and abdomen movements, and air
2
Polysomnography (PSG)\: comprehensive study including EEG, EOG, chin EMG, leg EMG, and respiratory polygraphy.
Multiple sleep latency testing (MSLT)\: measures sleep latency and REM onset over multiple nap opportunities.
Epworth sleepiness scale\: assesses daytime sleepiness propensity, scoring 0-24, with higher scores indicating more
severe sleepiness.
Obstructive sleep apnoea (OSA)\: upper airway obstruction during sleep causing apnoea and hypoxia.
Risk factors\: obesity, male sex, large neck size, craniofacial abnormalities, smoking, hypothyroidism, acromegaly.
Symptoms\: unrefreshing sleep, excessive daytime sleepiness (EDS), morning headaches, poor memory, and reduced
libido.
Investigations\: pulse oximetry, respiratory polygraphy, polysomnography.
Management\: weight loss, CPAP, mandibular advancement device, adenotonsillectomy in children.
Insomnia\: inability to sleep.
Causes\: physical conditions, primary sleep disorders, psychiatric causes, drugs, delayed sleep phase syndrome.
Symptoms\: daytime sleepiness, poor concentration, low mood, physical pain, nocturia.
Management\: address underlying cause, sleep hygiene, CBT, short-term hypnotics, melatonin for older patients.
Narcolepsy\: brain's inability to regulate sleep-wake cycle.
Symptoms\: EDS, disrupted nighttime sleep, cataplexy, hypnagogic/hypnopompic hallucinations, sleep paralysis.
Investigations\: PSG, MSLT, CSF orexin levels.
Management\: good sleep hygiene, scheduled naps, CNS stimulants, antidepressants, sodium oxybate, support at
work/school.
Restless legs syndrome (RLS)\: urge to move legs, worse at night or when resting.
Symptoms\: urge to move legs, abnormal sensations, involuntary jerks, insomnia, fatigue.
Management\: lifestyle changes, treat underlying cause, dopamine agonists, other medications (L-dopa, gabapentin,
pregabalin).
Other sleep disorders\:
Idiopathic central nervous system hypersomnia\: excessive day and night time sleepiness.
Parasomnias\: unusual activity/experiences during sleep (e.g., sleepwalking, night terrors, REM sleep behaviour disorder).
Nocturnal epilepsy\: frontal lobe seizures at night causing unusual activity.
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Introduction
Sleep disorders are common and can present in the context of multiple medical specialities. Having an awareness of sleep
disorders is useful across specialities including respiratory medicine, general practice and neurology.
This article will outline the presentation, investigations and management of four conditions a
clinical case-based quiz to test your knowledge.
Sleep studies and diagnostic scores
The diagnosis of sleep disorders often relies on sleep studies, details of which are included in the table below.
Table 1. An overview of sleep studies.
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Type of sleep study Description
Pulse oximetry
Respiratory
polygraphy (rPG)
Polysomnography
(PSG)
Multiple sleep
latency testing
(MSLT)
The simplest sleep study. The patient wears an
oximeter to record peripheral oxygen saturation (SpO )
2
and pulse rate overnight, usually at home.
Following a
pulse oximeter to measure SpO 2
and pulse, straps to
measure chest and abdomen movements, and a
sensor in the nostrils overnight, usually at home.
A more comprehensive study that records overnight
electroencephalogram (EEG), electrooculogram (EOG)
and chin electromyogram (EMG) to allow staging of
sleep and wake, alongside respiratory polygraphy, leg
EMG and video/audio. Usually carried out in a sleep
lab.
Similar to (and usually follows some) PSG studies, but
without polygraphy. The patient is given multiple nap
opportunities over a day in a sleep lab.
The Epworth sleepiness scale (abridged version below) is a questionnaire developed to quantify daytime sleepiness
propensity.
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It is not speci
obstructive sleep apnoea (OSA) and narcolepsy.
Epworth sleepiness scale
How likely are you to doze o
0 = w o u l d n e v e r d o z e , 1 = s l i g h t c h a n c e o f d o z i n g, 2 = m o d e r a t e c h a n c e o f d o z i n g, 3 = h i gh c h a n c e o f d o z i n g
1. Sitting and reading
2. Watching television
3. Sitting still in a public place (e.g. a theatre)
4. As a passenger in a car for an hour without a break
5. Lying down to rest in the afternoon when circumstances allow
6. Sitting and talking to someone
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7. Sitting quietly after lunch without having drunk alcohol
8. In a car or bus while stopped for a few minutes in tra
Interpretation of total score\:
0-5\: lower normal daytime sleepiness
6-10\: normal daytime sleepiness
11-12\: mild excessive daytime sleepiness
13-15\: moderate excessive daytime sleepiness
16-24\: severe excessive daytime sleepiness
Obstructive sleep apnoea (OSA)
Obstructive sleep apnoea is a condition where the upper airway frequently becomes obstructed during sleep, resulting in
short periods of apnoea (not breathing).
Aetiology
Contraction of muscles in the tongue and palate hold the throat open against negative pressures during inspiration when
awake. These muscles become hypotonic during sleep, particularly rapid eye movement (REM) sleep, which can result in
partial or complete occlusion of the airway in patients with OSA.
A complete occlusion results in a period of apnoea and usually secondary hypoxia, terminating with the patient
momentarily arousing from sleep. These apnoeas can occur hundreds of times each night, resulting in highly disrupted
sleep. However, the episodes are so short that the patient is usually not aware of them.
Risk factors
Risk factors for OSA include\:
Obesity
Male sex
Increased collar size
Craniofacial abnormalities
Nasal congestion
Smoking
Hypothyroidism
Acromegaly
Respiratory depressant drugs (including alcohol)
Untreated OSA is associated with diabetes mellitus and is a risk factor for hypertension and other cardiovascular
diseases in later life.
Clinical features3
Typical symptoms of OSA include\:
Unrefreshing sleep
Excessive daytime sleepiness (EDS)\: consider assessing with the Epworth sleepiness scale and exclude other causes of
EDS such as poor sleep hygiene.
Morning headaches
Poor memory and attention
A feeling of choking at night
Reduced libido
Anyone who has seen the patient sleep may report loud snoring or episodes of not breathing (witnessed apnoeas).
Typical signs to look for on examination include\:
Large body habitus, including increased neck circumference
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Narrow pharynx or nasal passages, for example, due to enlarged tonsils
Signs of complications (e.g. pulmonary hypertension and cor pulmonale)
Investigations
Common investigations for OSA include\:
Pulse oximetry
Respiratory polygraphy
Oxygen saturations from overnight pulse oximetry can be used to calculate the oxygen desaturation index (ODI, the
number of oxygen desaturations during sleep per hour). This score can be used diagnostically\:
ODI \< 5\: normal
5 ≤ ODI \< 15\: mild OSA
15 ≤ ODI \< 30\: moderate OSA
ODI ≥ 30\: severe OSA
Figure 1 is an oximetry sleep study showing frequent oxygen desaturations (ODI 24/hour) in keeping with moderate
obstructive sleep apnoea. The top (red) trace is oxygen saturation (SpO2%) and the bottom (blue) trace is the pulse rate.
Note the close association of pulse rate variability with SpO2 dips.
Figure 1.Pulse oximetry sleep study showing frequent oxygen desaturations suggestive of moderate OSA.
Some sleep centres use respiratory polygraphy to instead calculate the apnoea-hypopnoea index (AHI). This is more
sensitive and speci
In some cases, if these sleep studies are inconclusive, a more complex sleep study, called a polysomnogram, may be
required.
Management
Management of OSA depends on the severity and patient choice but may include\:
4
Conservative/lifestyle measures\: weight loss, reduce alcohol consumption, smoking cessation.
Continuous positive airway pressure (CPAP)\: positive pressure to keep the airway open, given continuously via a mask
overnight.
Mandibular advancement device\: an intraoral splint worn during the night to increase airway size and reduce
collapsibility.
Adenotonsillectomy\: can help children with OSA secondary to enlarged tonsils.
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Insomnia
Insomnia describes being unable to sleep at night.
Aetiology
Common causes of insomnia include\:
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Primary physical conditions\: for example, uncontrolled pain or frequent nocturia.
Primary sleep disorders\: narcolepsy or restless legs syndrome.
Psychiatric causes\: depression, anxiety, mania, delirium and dementia.
Drugs\: including both stimulants such as ca
and alcohol. Several prescription drugs can disturb sleep, including steroids and dopamine agonists.
Delayed sleep phase syndrome may mimic insomnia. This syndrome occurs when the circadian rhythm is shifted back so
patients cannot get to sleep until early the next day but sleep a normal amount once they are asleep.
Some patients may be diagnosed with primary insomnia when no underlying cause can be found.
Clinical features
The nature and extent of insomnia should
How much sleep the patient thinks they are getting
Whether they cannot get to sleep, cannot maintain sleep, or wake up early
It is important to take a thorough medical, drug, social and family history, in order to identify factors underlying or
contributing to insomnia.
Typical symptoms of insomnia include\:
Daytime sleepiness and physical fatigue
Poor concentration and low mood
Other symptoms of depression, anxiety and other psychiatric conditions
Physical pain and nocturia
Investigations
Investigations are guided by history. The patient can be asked to complete a sleep diary to track their sleep habits.
Management
Management options for insomnia include\:
Addressing the underlying cause where possible
Good sleep hygiene, including lifestyle changes such as avoidance of ca
Cognitive behavioural therapy or counselling for psychological disorders
Hypnotic drugs may be prescribed as a short-term solution only, and include short-acting benzodiazepines, or non-
benzodiazepine hypnotics such as zopiclone and zolpidem.
Modi
Narcolepsy
Narcolepsy is a rare condition in which the brain loses its normal ability to regulate the sleep-wake cycle. There are two
widely recognised subtypes\: type 1 and type 2.
Patients with type 1 narcolepsy experience cataplexy (conscious collapse), and have low levels of orexin in their cerebral
spinal
Aetiology
Orexin (hypocretin) is a neurotransmitter involved in the regulation of sleep, wakefulness and appetite. Loss of orexin-
secreting neurons in the hypothalamus results in narcolepsy. Most cases are thought to be due to autoimmunity.
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There is a strong genetic associated with certain HLA-subtypes, but environmental factors may also play a role. For
example, there is epidemiological evidence that in
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Clinical features
Typical symptoms of narcolepsy include\:
Excessive daytime sleepiness (EDS)\: exclude other causes.
Disrupted nighttime sleep and/or vivid dreams.
Cataplexy\:
“conscious collapse” caused by muscle atonia, often in response to sudden emotion such as laughter or
surprise; rarely seen by the clinician so diagnosis often based on the characteristic description.
Hypnagogic/hypnopompic hallucinations\: dream-like hallucinations at the point of emerging from/entering REM sleep.
Sleep paralysis\: paralysis while awake and conscious, again at the transition between REM sleep and wakefulness.
Investigations
Common investigations for narcolepsy include\:
Polysomnography (PSG)
Multiple sleep latency testing (MSLT)
The time it takes to fall asleep is known as sleep latency. Usually, REM sleep
but if REM sleep occurs within 15 minutes of sleep onset, it is known as SOREM (sleep-onset REM).
Figure 2 shows the results from MSLT in a patient with narcolepsy demonstrating a mean sleep latency of 0.9 minutes and
3 episodes of SOREM.
Figure 2.Multiple sleep latency testing study.
Other investigations that may be of use include\:
CSF orexin levels\: if low/undetectable and associated with EDS suggests type 1 narcolepsy, even in the absence of
cataplexy.
population.
HLA-testing is of limited use as the allele seen in most cases of narcolepsy with cataplexy is also common in the general
Management
Management options for narcolepsy include\:
Good sleep hygiene\: always important but rarely e
Scheduled naps\: can be helpful (brief e.g. 20 minutes).
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Central nervous system stimulants (for excessive sleepiness)\: moda
and pitolisant.
Anti-depressants (for cataplexy)\: clomipramine, selective serotonin reuptake inhibitors, venlafaxine.
Sodium oxybate\: potent sedative\: improves nocturnal sleep quality, EDS, and cataplexy.
Support\: with school or work (e.g. deadline
Restless legs syndrome (RLS or Willis-Ekbom disease)
Restless legs syndrome is a disorder of sensorimotor processing in the brain resulting in the urge to move the legs. It is
associated with abnormal sensations and often worse at night or when resting.
Aetiology
The pathophysiology is not fully understood but may involve brain iron de
neurotransmission. 7
The condition may be hereditary and tends to worsen with age.
Clinical features
Typical symptoms of restless legs syndrome include\:
Urge to move the legs, worse when sitting or lying still in the evenings
Involuntary jerks if the legs are kept still
Abnormal sensations in the legs (e.g. pins and needles, burning, crawling, pulling, itching or aching)
Symptoms can be relieved by movement or sometimes if the legs are kept cool or massaged
Secondary insomnia and fatigue
History from bed partner may describe periodic limb movements in sleep
Co-existent OSA (can exacerbate)
Signs to look for on examination include\:
Conjunctival pallor, angular cheilosis, koilonychia, atrophic glossitis\: RLS may be a sign of iron de
Signs of peripheral neuropathy (including from diabetes mellitus)\: RLS can be a complication.
Resting tremor, rigidity, bradykinesia\: RLS can occur with Parkinson's disease.
Investigations
History is key but investigations that may aid the diagnosis of RLS include\:
Actigraphy\: a type of sleep study monitoring limb movements.
Polysomnography.
Management
Management options for restless legs syndrome include\:
Lifestyle changes, including sleep hygiene and reduction/avoidance of ca
Treatment of underlying cause if relevant
Medical management may include dopamine agonists. Other medications sometimes used include L-dopa, gabapentin,
pregabalin, benzodiazepines and opioids.
Other conditions a
Idiopathic central nervous system hypersomnia is a poorly understood condition characterised by excessive day and
night time sleepiness. It should be considered when no primary cause for excessive day time sleepiness can be found.
Parasomnias are a group of disorders characterised by unusual activity or experiences arising from sleep or sleep-wake
transitions. This includes non-rapid eye movement (NREM) parasomnias such as sleepwalking and talking, night terrors,
confusional arousal (partial awakening with confusion) and REM sleep behaviour disorder (acting out dreams), isolated
sleep paralysis and hypnogogic/hypnopompic hallucinations.
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Nocturnal epilepsy is caused by a frontal lobe seizure at night, typically involving screaming, frantic movements and a
sensation of fear.
Further information on the classird
of Sleep Disorders (ICSD).
8
edition of the International Classi
Case studies
Case one
A 27-year-old woman presents to her GP with di
worse, and she now estimates only around 4 hours of sleep each night. She reports feeling increasingly tired during the day
and is struggling to concentrate at work. She has been told by partners in the past that she snores at night but does not
report any morning headaches. On further questioning, she reveals she has been feeling low in mood since she split up
with her partner around a month ago, which she feels was her fault.
She drinks two cups of co
medications. She scores 10 on the Epworth sleepiness scale and her body mass index is 36. Physical examination is
unremarkable.
She is given an oximeter for a simple overnight sleep study at home. The results give a 4% oxygen desaturation index (ODI)
of 4/hour.
[expand title=
"What is the most likely diagnosis?"]
The most likely diagnosis is insomnia secondary to mild depression. The history includes four of the ten ICD-10 diagnostic
criteria for depression - depressed mood, reduced energy, ideas of guilt and reduced concentration – for over 2 weeks.
This is su
habitus and snoring history, the ODI of less than 5 makes this diagnosis unlikely.
[/expand]
[expand title=
"How would you initially manage this patient?"]
Management of insomnia should include addressing the underlying cause. In this case, mild depression may be treated
with cognitive behavioural therapy and lifestyle changes. Many of the lifestyle changes recommended for mild
depression may also help insomnia in their own right, including regular exercise, good sleep hygiene and reduction of
ca
[/expand]
Case two
A 14-year-old boy is referred to a neurologist after an episode of conscious collapse, diagnosed by the GP as an atonic
seizure. The episode occurred while he was out with friends. He collapsed to the
recovered almost immediately, with no lasting confusion or weakness.
On further questioning, he reports feeling very tired during the day and frequent naps during lessons at school. However,
he often has trouble getting to sleep at night. In the past, he has had two episodes of waking up and being unable to move.
He has no past medical history of note and takes no regular medications.
He scores 15 on the Epworth sleepiness scale and neurological examination is unremarkable. The neurologist refers the
patient for polysomnography and multiple sleep latency testing. PSG shows rapid sleep onset overnight, minor non-
speci
3.5 minutes and REM sleep was seen on 2 of the naps.
[expand title=
"Is atonic seizure the correct diagnosis?"]
Atonic seizure is an unlikely diagnosis, given the patient did not have a post-ictal phase of delayed recovery. Narcolepsy is
more likely based on the history, which includes features of excessive daytime sleepiness (con
sleepiness scale score), disrupted nighttime sleep and past episodes of sleep paralysis. The recent ‘conscious collapse’ is
likely to be an episode of cataplexy.
[/expand]
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[expand title=
"How should this patient be managed?"]
Although this is his
stimulants such as moda
oxybate may be considered.
[/expand]
Case three
A 47-year-old man is referred to the sleep clinic after his wife noticed him frequently stop breathing when asleep overnight.
He has always been a loud snorer but this has been getting worse. He has been otherwise well over the past few years,
although sometimes wakes with a headache that subsides over 1 or 2 hours, and has experienced progressively severe
daytime sleepiness over the past few months.
He drinks 10-15 units of alcohol a week and has a 30 pack-year smoking history. He has a past medical history of type 2
diabetes, for which he takes metformin, and asthma, for which he takes an inhaled corticosteroid and salbutamol.
He scores 14 on the Epworth sleepiness scale, and his body mass index is 37. Physical examination otherwise reveals a
thick neck and crowded oropharynx. He is given a home oximeter for a simple sleep study, which results in an ODI of
32/hour.
[expand title=
"What is the most likely diagnosis?"]
This patient gives a classical history of obstructive sleep apnoea. Risk factors include age, male gender, body habitus,
alcohol intake and smoking history. The ODI con
[/expand]
[expand title=
"What are the risks if this condition remains untreated?"]
Untreated OSA is associated with increased risk of cardiovascular disease. This patient already has multiple other risk
factors, including alcohol intake, smoking history, obesity and diabetes.
[/expand]
[expand title=
"How should this patient be managed?"]
This patient quali
on cardiovascular risks are possible but remain unproven (beyond refractory hypertension). Lifestyle factors should also be
addressed.
[/expand]
References
Reference images
Figure 1 and 2 provided by the Respiratory Support and Sleep Centre at the Royal Papworth Hospital.
Reference texts
Royal Papworth Hospital NHS Foundation Trust. S l e e p i n v e s t i g a t i o n s a t R o y a l P a p w o r t h H o s p i t a l . Available from\: [LINK]
British Lung Foundation, Obstructive Sleep Apnoea Diagnosis, Epworth Sleepiness Scale. Available from\: [LINK]
th
Kumar and Clark’s Clinical Medicine, 9 Edition, R e s p i r a t o r y D i s e a s e , p. 1085-1086.
National Institute of Health and Care Excellence CKS. O b s t r u c t i v e S l e e p A p n o e a , S c e n a r i o \: M a n a ge m e n t o f S l e e p A p n o e a .
Published in 2015. Available from\: [LINK]
Dauvilliers, Y. & Barateau, L. Narcolepsy and Other Central Hypersomnias. C O N T I N U U M L i f e l o n g L e a r n i n g i n N e u r o l o g y 23,
989–1004 (2017).
th
Kumar and Clark’s Clinical Medicine, 9 Edition, P s y c h o l o g i c a l M e d i c i n e , p. 905
Venkateshiah, S. B. & Ioachimescu, O. C. Restless Legs Syndrome. C r i t i c a l C a r e C l i n i c s 31, 459–472 (2015).
Sateia, Michael J, International Classi
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Reviewer
Dr Tim Quinnell
Consultant respiratory and sleep disorders physician
Related notes
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Test yourself
Contents
Introduction
Sleep studies and diagnostic scores
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