Sleep–Wake Disorders Overview

Vocabulary flashcards covering key terms, disorders, physiology, diagnostics, and treatments discussed in the lecture on sleep–wake disorders.

Sleep

A required, active brain process with multiple distinct stages necessary for proper cognitive, emotional, and physiologic functioning.

Non-Rapid Eye Movement (NREM) Sleep

Sleep state divided into stages 1-4, characterized by progressively slower EEG activity, reduced muscle tone, and minimal dreaming.

Rapid Eye Movement (REM) Sleep

Active sleep stage with low-voltage mixed-frequency EEG, rapid eye movements, atonia, and vivid dreaming.

Sleep Spindle

12–14 Hz burst of EEG activity characteristic of NREM stage 2 sleep.

K-Complex

High-voltage biphasic wave that marks NREM stage 2 and aids in arousal suppression.

Sleep Efficiency

Percentage of total time in bed actually spent asleep.

Insomnia Disorder

Persistent difficulty initiating, maintaining, or returning to sleep causing daytime impairment (≥3 nights/week for ≥3 months).

Psychophysiologic Insomnia (PPI)

Insomnia maintained by conditioned arousal and worry about sleep; bed cues evoke wakefulness.

Idiopathic Insomnia

Lifelong inability to obtain adequate sleep that predates other conditions and lacks identifiable cause.

Paradoxical Insomnia

Complaint of severe insomnia despite objective evidence of near-normal sleep on polysomnography.

Inadequate Sleep Hygiene

Insomnia due to behaviors that increase arousal or disrupt circadian schedule (e.g., caffeine, irregular bedtimes).

Behavioral Insomnia of Childhood

Pediatric sleep onset or maintenance problem linked to inappropriate sleep associations or limit-setting failure.

Hypersomnolence Disorder

Excessive daytime sleepiness despite ≥7 h sleep, with long, unrefreshing naps or prolonged main sleep (≥3 months).

Idiopathic Hypersomnia

Chronic excessive sleepiness of unknown cause, normal REM latency, often requiring >10 h sleep/night.

Kleine–Levin Syndrome

Recurrent hypersomnia episodes (sleeping 18-20 h/day) with hyperphagia, hypersexuality, and behavioral change, mainly in adolescent males.

Narcolepsy

Chronic neurologic disorder marked by daytime sleep attacks and sleep-onset REM periods; often linked to hypocretin deficiency.

Cataplexy

Sudden, brief loss of muscle tone triggered by emotion, with preserved consciousness, characteristic of narcolepsy type 1.

Sleep Paralysis

Transient inability to move at sleep onset or upon awakening, sometimes accompanied by hallucinations.

Hypnagogic / Hypnopompic Hallucinations

Vivid dream-like perceptions occurring at sleep onset (hypnagogic) or upon awakening (hypnopompic).

Sleep-Related Breathing Disorders

Group of conditions with abnormal respiration during sleep leading to arousals and daytime sleepiness.

Obstructive Sleep Apnea (OSA)

Repeated upper-airway collapse during sleep producing apneas/hypopneas, oxygen desaturation, and arousals.

Central Sleep Apnea (CSA)

Apnea caused by diminished respiratory drive rather than airway obstruction; includes Cheyne–Stokes breathing pattern.

Sleep-Related Hypoventilation

Sustained elevated CO₂ or low O₂ during sleep due to inadequate ventilation (e.g., obesity hypoventilation).

Positive Airway Pressure (PAP)

First-line OSA therapy that pneumatically splints the airway with continuous (CPAP) or bilevel pressure.

Automatic PAP (APAP)

Device that adjusts pressure breath-by-breath based on airflow resistance to treat sleep apnea.

Oral Appliance Therapy

Mandibular advancement or tongue-retaining device used to treat mild-to-moderate OSA.

Uvulopalatopharyngoplasty (UPPP)

Surgical removal of redundant soft-palate tissue to enlarge airway in selected OSA patients.

Circadian Rhythm Sleep–Wake Disorders

Sleep disturbances caused by misalignment between internal circadian clock and desired schedule.

Delayed Sleep Phase Disorder

Chronic pattern of late sleep onset and awakening; ‘night-owl’ phenotype that improves with phase advance.

Advanced Sleep Phase Disorder

Early evening sleepiness and early morning awakening; ‘lark’ phenotype often familial.

Non-24-Hour Sleep–Wake Disorder

Free-running circadian rhythm longer (or shorter) than 24 h, common in totally blind individuals.

Irregular Sleep–Wake Rhythm

Lack of clear circadian pattern with multiple short sleep bouts spread over 24 h.

Shift Work Disorder

Insomnia and/or excessive sleepiness associated with work hours overlapping the habitual sleep period.

Jet Lag Disorder

Temporary circadian misalignment and sleep disturbance following rapid travel across ≥2 time zones.

Bright Light Therapy

Timed exposure to 2 000–10 000 lux (often blue-enriched) light to phase-shift the circadian clock.

Melatonin

Pineal hormone used exogenously to facilitate circadian phase-shifting or sleep onset.

Chronotherapy

Systematic daily phase delay (or advance) of sleep time to realign circadian rhythm with desired schedule.

Parasomnia

Undesirable physical or experiential events occurring during entry into, within, or on arousal from sleep.

NREM Sleep Arousal Disorders

Group of parasomnias (sleepwalking, sleep terrors, confusional arousals) arising from slow-wave sleep.

Sleepwalking (Somnambulism)

Complex motor behavior from slow-wave sleep with reduced awareness and subsequent amnesia.

Sleep Terrors

Abrupt awakenings from slow-wave sleep with scream, tachycardia, and intense fear, followed by amnesia.

Confusional Arousal

Partial awakening with disorientation and automatic behaviors, typically in children.

Sleep-Related Eating Disorder

Recurrent episodes of eating after partial arousal from NREM sleep, often without memory and with injury risk.

REM Sleep Behavior Disorder (RBD)

Loss of REM atonia causing dream enactment behaviors; frequently prodromal to synucleinopathy.

Nightmare Disorder

Repeated extended, dysphoric dreams that awaken the sleeper and cause distress with vivid recall.

Recurrent Isolated Sleep Paralysis

Episodes of REM-related atonia intruding into wakefulness without other narcolepsy symptoms.

Exploding Head Syndrome

Benign parasomnia where a loud imagined noise or explosion is perceived during sleep-wake transition.

Sleep-Related Hallucinations

Vivid sensory perceptions occurring at sleep onset or awakening, distinct from dreams and psychosis.

Sleep Enuresis

Involuntary urination during sleep after expected bladder control age; primary or secondary forms.

Restless Legs Syndrome (RLS)

Urge to move legs with uncomfortable sensations, worse at rest and evening, relieved by movement.

Periodic Limb Movement Disorder (PLMD)

Repetitive limb jerks (0.5–5 s) every 20–40 s during NREM sleep causing sleep fragmentation.

Sleep-Related Bruxism

Involuntary grinding or clenching of teeth during sleep, leading to dental wear and jaw pain.

Sleep-Related Leg Cramps

Painful calf or foot muscle contractions awakening sleeper; associated with metabolic or pregnancy states.

Sleep-Related Rhythmic Movement Disorder

Repetitive head banging or body rocking during drowsiness or light sleep, commonly in infants.

Benign Sleep Myoclonus of Infancy

Self-limited limb jerks in quiet sleep of neonates without neurologic disease.

Propriospinal Myoclonus at Sleep Onset

Axial jerks starting in trunk muscles that delay sleep; may respond to clonazepam.

Multiple Sleep Latency Test (MSLT)

Daytime study providing five nap opportunities to quantify sleepiness and detect sleep-onset REM.

Maintenance of Wakefulness Test (MWT)

Objective measure of ability to remain awake during quiet daytime periods; used for treatment assessment.

Polysomnography

Comprehensive overnight recording of EEG, EOG, EMG, airflow, effort, oximetry, and more to diagnose sleep disorders.

Actigraphy

Wrist-worn accelerometer tracking rest-activity cycles over days to assess sleep patterns and circadian rhythm.

Stimulus Control Therapy

Behavioral insomnia treatment that re-associates bed with sleep by strict rules (bed only for sleep, fixed rising time, etc.).

Sleep Restriction Therapy

Technique limiting time in bed to actual sleep time to consolidate sleep and increase efficiency.

Cognitive-Behavioral Therapy for Insomnia (CBTi)

Multicomponent program using cognitive restructuring, stimulus control, relaxation, and sleep hygiene to treat chronic insomnia.

Paradoxical Intention

Cognitive technique instructing insomniacs to try to remain awake, reducing performance anxiety and sleep latency.

Positive Airway Pressure Adherence

Consistent nightly PAP use ≥4 h, essential for therapeutic benefit in OSA.

Modafinil

Wake-promoting agent used for narcolepsy, residual OSA sleepiness, and shift-work disorder.

Armodafinil

R-enantiomer of modafinil offering longer duration wake promotion.

Pitolisant

Histamine H3-receptor inverse agonist approved to treat daytime sleepiness in narcolepsy.

Solriamfetol

Selective norepinephrine-dopamine reuptake inhibitor approved for EDS in narcolepsy and OSA.

Sodium Oxybate

GABA-B agonist improving cataplexy, fragmented sleep, and daytime sleepiness in narcolepsy.

Prazosin

α1-adrenergic blocker with evidence reducing PTSD-related nightmares.

Acetazolamide

Carbonic anhydrase inhibitor used to treat high-altitude CSA by stimulating ventilation via metabolic acidosis.

Cheyne–Stokes Breathing

Crescendo–decrescendo tidal volume cycles with central apneas, often in heart failure or stroke.

Sleep Hygiene

Set of behavioral practices (regular schedule, avoid caffeine, cool dark bedroom, etc.) that promote healthy sleep.

Sleep Log

Daily self-report record of bedtimes, awakenings, naps, and substance use to track sleep patterns.