Sleep Disorders: Narcolepsy, RLS, Parasomnias, and Other Sleep Conditions

Introduction

Sleep disorders encompass a wide range of conditions that affect sleep quality, timing, and associated behaviors. This guide covers narcolepsy, restless legs syndrome (Willis-Ekbom disease), parasomnias (NREM and REM-related), periodic limb movement disorder, and other clinically significant sleep conditions. Accurate diagnosis requires clinical evaluation and often polysomnography with multiple sleep latency testing.

Narcolepsy

Classification

Type	Hypocretin	Cataplexy	HLA Association	Prevalence
Type 1 (Narcolepsy with cataplexy)	Low/absent (<110 pg/mL)	Present	HLA-DQB1*06:02 (90-98%)	0.02-0.05%
Type 2 (Narcolepsy without cataplexy)	Normal	Absent	HLA-DQB1*06:02 (40-60%)	Less common than type 1

Pathophysiology

Aspect	Detail
Hypocretin/orexin	Neuropeptide produced by lateral hypothalamus; promotes wakefulness and stabilizes sleep-wake transitions
Cell loss	Autoimmune destruction of >90% of hypocretin-producing neurons in type 1 narcolepsy
Trigger	Genetic susceptibility (HLA) + environmental trigger (likely infection, possibly H1N1 influenza or streptococcus)
Hypothesized mechanism	Molecular mimicry: T-cell response to antigen cross-reacts with hypocretin neurons
Onset	Gradual over weeks to months; typically in adolescence or young adulthood

Clinical Features

Symptom	Description	Frequency
Excessive daytime sleepiness	Irresistible sleep attacks, automatic behaviors, prolonged sleep (12+ hours)	100%
Cataplexy	Sudden bilateral loss of muscle tone triggered by strong emotions (laughter, surprise, anger)	60-75% (type 1)
Hypnagogic/hypnopompic hallucinations	Vivid, often frightening hallucinatory experiences at sleep onset (hypnagogic) or upon awakening (hypnopompic)	30-60%
Sleep paralysis	Inability to move or speak upon falling asleep or waking; often with hallucinations	25-50%
Fragmented nighttime sleep	Frequent awakenings, vivid dreams, periodic limb movements	50-80%

Cataplexy Characteristics

Feature	Description
Triggers	Laughter (most common), surprise, anger, excitement, anticipation
Duration	Seconds to 2 minutes
Consciousness	Fully aware during episodes
Distribution	Partial (buckling knees, drooping eyelids, slurred speech, head drop) to complete (falling down)
Frequency	Variable: few/year to dozens/day
Preservation	Respiratory muscles, eye muscles spared

Diagnosis

Test	Purpose	Findings
Polysomnography (PSG)	Rule out other causes, document sleep	Short sleep latency (<10 min), SOREM (sleep onset REM within 15 min), fragmented sleep
Multiple Sleep Latency Test (MSLT)	Confirm pathologic sleepiness	Mean sleep latency <8 minutes; 2+ SOREMs (diagnostic for narcolepsy)
Hypocretin measurement (CSF)	Confirm type 1 narcolepsy	<110 pg/mL; highly specific but invasive
HLA typing	Supportive evidence	DQB1*06:02 present in 90-98% of type 1, 12-35% of general population

Treatment

Symptom	Medication	Mechanism	Dosing	Side Effects
EDS	Modafinil/armodafinil	Weak dopamine reuptake inhibition	Modafinil 200-400 mg AM; Armodafinil 150-250 mg AM	Headache, anxiety, reduced OCP efficacy
EDS	Solriamfetol (Sunosi)	Dopamine/norepinephrine reuptake inhibition	75-150 mg AM	Headache, nausea, anxiety, palpitations
EDS	Methylphenidate (Ritalin, Concerta)	Dopamine/norepinephrine reuptake inhibition	10-60 mg/day	Tolerance, hypertension, anxiety
EDS	Amphetamine/dextroamphetamine (Adderall)	Dopamine release + reuptake inhibition	5-60 mg/day	Abuse potential, tolerance, cardiac effects
EDS	Pitolisant (Wakix)	Histamine H3 receptor inverse agonist	4.4-35.6 mg AM	Insomnia, headache, nausea, anxiety
EDS	Sodium oxybate (Xyrem/Xywav)	GABA-B receptor agonist	4.5-9 g/night (split dose)	Nausea, dizziness, enuresis, sleepwalking, respiratory depression
Cataplexy	Sodium oxybate/Xywav	Same as above	Same as above	Same as above
Cataplexy	Venlafaxine	SNRI (inhibits REM)	37.5-150 mg AM or BID	Nausea, sexual dysfunction, hypertension
Cataplexy	Fluoxetine	SSRI (inhibits REM)	20-60 mg AM	Insomnia, sexual dysfunction
Cataplexy	Clomipramine	Tricyclic antidepressant	10-75 mg	Anticholinergic, weight gain, QTc prolongation
Sleep fragmentation	Sodium oxybate/Xywav	Improves nighttime sleep consolidation	As above	As above

Lifestyle Management

Strategy	Recommendation
Scheduled naps	15-20 minute naps 2-3 times daily (briefly improves alertness)
Sleep schedule	Consistent bedtime and wake time
Driving safety	Strategic napping before driving, stop every 2 hours, avoid driving if severely sleepy
Avoid	Alcohol, heavy meals, sleep deprivation
Support groups	Narcolepsy Network, Wake Up Narcolepsy

Restless Legs Syndrome (Willis-Ekbom Disease)

Diagnostic Criteria (IRLS Group)

Criterion	Description
1	Urge to move the legs (or arms) usually accompanied by unpleasant sensations
2	Symptoms begin or worsen during periods of rest or inactivity
3	Symptoms partially or totally relieved by movement (walking, stretching, or other activity)
4	Symptoms occur or worsen in the evening or night
5	Not solely accounted for by another condition (myalgia, venous stasis, arthritis, leg cramps, positional discomfort)
6 (Supportive)	Family history of RLS; periodic limb movements; response to dopaminergic therapy

Clinical Features

Feature	Description
Sensations	Crawling, creeping, pulling, aching, tingling, electric, or “Coca-Cola in the veins”
Location	Usually legs (calves, thighs, feet); may involve arms in severe cases
Timing	Symptoms worst at night, especially when lying down; circadian pattern
Associated condition	Periodic limb movement disorder (PLMD) - 80-90% of RLS patients
Sleep impact	Prolonged sleep latency, frequent awakenings, reduced sleep efficiency
Daytime impact	Fatigue, sleepiness, reduced quality of life
Prevalence	5-15% of population; 2-3% moderate-severe; increases with age
Sex ratio	Female > Male (2:1)

Etiology

Factor	Contribution
Iron deficiency	Most common secondary cause; low brain iron even with normal serum ferritin
Genetics	BTBD9, MEIS1, PTPRD, MAP2K5/SKOR1 loci identified
Dopamine dysfunction	Central dopaminergic system abnormality (responds to dopamine agonists)
Pregnancy	20-30% affected (especially third trimester); usually resolves after delivery
Renal failure	20-50% of dialysis patients; associated with anemia and iron deficiency
Medications	SSRIs, SNRIs, antihistamines, antipsychotics, caffeine, alcohol
Peripheral neuropathy	Associated with diabetes, alcohol, chemotherapy

Iron Deficiency Workup

Test	Target
Serum ferritin	Goal >50-100 ng/mL (treat if <50)
Iron saturation	Goal >20%
Serum iron	Normal range
TIBC	Normal range
CRP	Normal (ferritin is acute phase reactant)

Treatment

Severity	Treatment	Dose	Notes
Mild (intermittent)	Non-pharmacologic	N/A	Avoid triggers, exercise, stretching, massage, warm bath, mental activity
Mild-intermittent	Levodopa/carbidopa (Sinemet)	100/25 mg	Risk of augmentation; limit to 1-2 doses/night, not daily
Moderate-severe (daily)	Gabapentin (Neurontin)	300-1200 mg at night	First-line; good for coincident pain, insomnia
Moderate-severe (daily)	Pregabalin (Lyrica)	50-300 mg at night	Alternative to gabapentin
Moderate-severe (daily)	Gabapentin enacarbil (Horizant)	600 mg at night	FDA-approved for RLS; extended release
Moderate-severe (daily)	Ropinirole (Requip)	0.25-4 mg at night	Dopamine agonist; risk of augmentation, impulse control disorders
Moderate-severe (daily)	Pramipexole (Mirapex)	0.125-0.5 mg at night	Similar to ropinirole
Moderate-severe (daily)	Rotigotine patch (Neupro)	1-3 mg/24h transdermal	Continuous delivery; lower augmentation risk
Refractory	Opioids (tramadol, oxycodone)	Low dose	Last resort; risk of dependence, tolerance
Iron deficiency	Ferrous sulfate 325 mg + vitamin C 250 mg qd or IV iron	Serum ferritin >100	Treat ferritin <50 (may be effective up to <100)

Augmentation (Complication of Dopaminergic Treatment)

Feature	Description
Definition	Earlier onset of symptoms, increased severity, spreading to previously unaffected body parts, shorter duration of medication effect
Risk factors	Higher doses of levodopa/dopamine agonists, longer duration of treatment, low ferritin
Management	Gradual taper of dopaminergic medication, switch to alpha-2-delta ligand (gabapentin), or rotigotine patch
Prevention	Use lowest effective dose, avoid daily use of levodopa, maintain ferritin >50-100 ng/mL, limit to monotherapy

Periodic Limb Movement Disorder (PLMD)

Aspect	Description
Definition	Periodic, repetitive movements of the legs (or arms) during sleep, causing sleep disruption
Movement pattern	Extension of big toe + dorsiflexion of ankle + partial flexion of knee and hip
Interval	Every 20-40 seconds
Duration	0.5-5 seconds
PLMS index	>15/hr (adults) or >5/hr (children) + clinical sleep disturbance
Association	80-90% of RLS patients; also in narcolepsy, REM behavior disorder, OSA, iron deficiency
Treatment	Same as RLS (gabapentin, dopamine agonists); treat underlying condition

Parasomnias

Classification

Category	Examples	Sleep Stage	Usually Occurs
NREM parasomnias	Sleepwalking, night terrors, confusional arousals, sleep eating	N3 (slow wave sleep)	First 1/3 of night
REM parasomnias	REM behavior disorder, nightmare disorder, recurrent isolated sleep paralysis	REM	Last 1/3 of night
Other	Sleep enuresis, exploding head syndrome, sleep-related hallucinations, sleep-related eating disorder	Various	Various

NREM Parasomnias (Disorders of Arousal)

Feature	Sleepwalking	Night Terrors	Confusional Arousals
Age	Children > adults	Children 4-12 years	All ages (peak in children)
Behavior	Walking, complex behaviors (opening doors, leaving house)	Screaming, crying, intense fear, autonomic arousal (tachycardia, diaphoresis)	Confusion, thrashing, sitting up, mumbling
Responsiveness	Difficult to awaken; confused if awakened	Difficult to awaken; inconsolable	May respond to soothing
Amnesia	Complete amnesia for event	Yes (may describe “something happened”)	Variable
Duration	Minutes to 30+ minutes	1-10 minutes	5-15 minutes
Trigger	Sleep deprivation, fever, stress, alcohol, medications	Same	Same
Treatment	Safety measures, treat underlying triggers, scheduled awakenings, clonazepam (adults)	Reassurance, avoid triggers, clonazepam (severe)	Reassurance, safety, treat triggers

Sleepwalking Precautions

Measure	Implementation
Secure doors and windows	Locks, alarms at top of doors (out of reach)
Remove tripping hazards	Clear floor, remove sharp objects
Block stairs	Safety gates at top and bottom
Secure dangerous items	Lock up knives, car keys, matches
Bedroom location	Ground floor bedroom preferred
Sleeping environment	Do not sleep in unfamiliar locations without supervision
Do not awaken	Guide gently back to bed rather than shaking awake

REM Behavior Disorder (RBD)

Aspect	Detail
Definition	Loss of normal REM atonia, leading to acting out of dreams
Dream content	Often violent, defending self against attack (being chased, fighting)
Behaviors	Talking, shouting, punching, kicking, jumping out of bed
Injury risk	Significant to patient and bed partner
Age	Typically >50 years (rarely younger except drug-induced)
Sex ratio	Male predominant (90%)
Association	Strong link to neurodegenerative disorders (Parkinson disease, dementia with Lewy bodies, multiple system atrophy)
Conversion rate	50-80% develop neurodegenerative disease within 10-15 years
Triggers	SSRIs, SNRIs, MAOIs, beta-blockers, alcohol withdrawal

Treatment	Intervention	Evidence
First-line	Clonazepam 0.5-2 mg qHS	80-90% effective
Second-line	Melatonin 3-15 mg qHS	70-80% effective; fewer side effects
Third-line	Pramipexole	Limited evidence
Bed safety	Pad floor, remove sharp objects, separate bed if needed	Essential
Follow-up	Neurologic evaluation for neurodegenerative risk	Annual screening for Parkinson, cognitive changes

Nightmare Disorder

Aspect	Description
Definition	Recurrent, lengthy, dysphoric dreams that awaken the sleeper
Timing	Usually last 1/3 of night (REM-dominant period)
Recall	Vivid recall of dream content
Distress	Causes significant distress or impairment
Prevalence	2-8% of adults; higher in trauma victims
Treatment	Image rehearsal therapy (IRT), prazosin (PTSD-related nightmares)

Sleep-Related Movement Disorders

Disorder	Description	Treatment
Bruxism (teeth grinding)	Rhythmic jaw muscle activity during sleep; tooth wear, jaw pain	Mouth guard, occlusal splint, stress management; clonazepam if severe
Periodic limb movements (PLMD)	Rhythmic leg movements during sleep with sleep disruption	Treat underlying RLS; gabapentin
Sleep-related leg cramps	Sudden intense muscle contraction (calf, foot) during sleep	Stretching, hydration, magnesium; quinine (not recommended due to toxicity risk)
Sleep-related rhythmic movement disorder	Body rocking, head banging, rolling during sleep onset	Common in children; resolves spontaneously; protective padding if needed

Central Disorders of Hypersomnolence

Disorder	Features	Diagnosis	Treatment
Narcolepsy type 1	EDS + cataplexy + SOREMs	PSG + MSLT + CSF hypocretin	Modafinil, sodium oxybate, pitolisant
Narcolepsy type 2	EDS + SOREMs (no cataplexy)	PSG + MSLT (normal hypocretin)	Modafinil, pitolisant
Idiopathic hypersomnia	EDS without cataplexy, long or unrefreshing naps, sleep drunkenness	PSG + MSLT (no SOREMs, or 1 SOREM + long sleep)	Modafinil, clarithromycin, flumazenil
Kleine-Levin syndrome	Episodic hypersomnia (1-2 weeks) + cognitive/mood changes, hyperphagia, hypersexuality	Clinical diagnosis; periods normal between episodes	Lithium (for prophylaxis), stimulants for acute episodes
Insufficient sleep syndrome	EDS due to voluntary sleep restriction	Sleep log showing <7 hours	Extend time in bed

Differential Diagnosis of Excessive Daytime Sleepiness

Condition	Key Distinguishing Feature
Sleep apnea (OSA)	Snoring, witnessed apneas, obesity, large neck
Narcolepsy	Cataplexy, hallucinations, sleep paralysis, SOREMs on MSLT
Idiopathic hypersomnia	Long sleep >10 hours, sleep drunkenness, no SOREMs
Insufficient sleep syndrome	Sleep log shows chronic sleep restriction
Depression	Anhedonia, low mood, insomnia or hypersomnia, responds to time of day
Circadian rhythm disorder	Sleep-wake timing misaligned with desired schedule
Medication side effect	Sedating medications (antihistamines, benzodiazepines, anticonvulsants, antidepressants)
Medical condition	Hypothyroidism, anemia, chronic fatigue syndrome, autoimmune disease
Shift work disorder	Symptoms temporally related to shift schedule