ABIM Sleep Medicine cheat sheet

NREM stage N1: theta (4-7 Hz) background, slow eye movements, vertex sharp waves; occupies 2-5% of total sleep time in adults.

NREM stage N2: sleep spindles (11-16 Hz, ≥0.5 s) and K-complexes (negative sharp wave followed by positive component, ≥0.5 s); 45-55% of total sleep time.

NREM stage N3 (slow-wave sleep): ≥20% of an epoch occupied by delta waves (0.5-2 Hz, >75 µV); predominant in first third of night.

REM sleep: low-amplitude mixed-frequency EEG, rapid eye movements, muscle atonia (chin EMG at lowest level); 20-25% of total sleep time; occurs in 4-6 cycles per night.

Sleep cycle length ~90 minutes; REM periods lengthen toward morning, while slow-wave sleep predominates early in the night.

Two-process model: homeostatic sleep pressure (Process S) rises with wakefulness and dissipates with sleep; circadian alerting signal (Process C, driven by suprachiasmatic nucleus) opposes sleep pressure.

Endogenous circadian period averages ~24.2 hours; light is the dominant zeitgeber, with melanopsin-containing retinal ganglion cells mediating non-image-forming effects.

Sleep onset normally occurs after the circadian low (core body temperature minimum, ~2-4 AM) and alertness peaks in the early evening (wake maintenance zone).

Normal sleep architecture changes with age: total sleep time and slow-wave sleep decline, sleep latency and wake after sleep onset increase, and circadian phase advances.

Insomnia disorder requires difficulty initiating or maintaining sleep, or early-morning awakening, with daytime impairment, occurring ≥3 nights/week for ≥3 months despite adequate opportunity to sleep.

Cognitive behavioral therapy for insomnia (CBT-I) is first-line treatment; components include stimulus control, sleep restriction, cognitive restructuring, sleep hygiene, and relaxation.

Stimulus control: use bed only for sleep and sex, go to bed only when sleepy, leave bed if unable to sleep within ~20 minutes, and maintain a fixed wake time.

Sleep restriction therapy: limit time in bed to average total sleep time (but not <5-6 hours), then extend by 15-30 minutes weekly as sleep efficiency exceeds 85-90%.

Sleep efficiency = total sleep time / time in bed × 100%; target ≥85-90% during sleep restriction.

FDA-approved hypnotics include benzodiazepines, non-benzodiazepine BZRAs (zolpidem, eszopiclone, zaleplon), melatonin receptor agonist (ramelteon), dual orexin receptor antagonists (suvorexant, lemborexant), and doxepin (low dose).

Benzodiazepines and BZRAs carry risks of tolerance, dependence, falls, and complex sleep behaviors; avoid in older adults and untreated obstructive sleep apnea.

Paradoxical intention and relaxation training are effective CBT-I components; sleep hygiene alone is insufficient as monotherapy.

Insomnia is a risk factor for depression, anxiety, and cardiometabolic disease; treat comorbid conditions concurrently.

Obstructive sleep apnea (OSA) diagnosis: apnea-hypopnea index (AHI) ≥5 with symptoms or comorbidities, or AHI ≥15 regardless of symptoms; hypopnea requires ≥30% flow reduction with ≥3% desaturation or arousal.

Apnea: ≥90% reduction in airflow for ≥10 seconds; central apnea: absent airflow with absent respiratory effort; mixed apnea begins central and becomes obstructive.

OSA severity: mild AHI 5-15, moderate 15-30, severe >30 events/hour.

STOP-BANG score ≥3 indicates high risk for OSA; components: Snoring, Tiredness, Observed apnea, Pressure (hypertension), BMI >35, Age >50, Neck circumference >40 cm, Gender male.

Positive airway pressure (PAP) is first-line for moderate-severe OSA; adherence defined as ≥4 hours/night on ≥70% of nights.

Oral appliances (mandibular advancement devices) are options for mild-moderate OSA or PAP intolerance; contraindicated with insufficient teeth or severe TMJ disorders.

Central sleep apnea with Cheyne-Stokes respiration is common in heart failure; treatment includes optimizing heart failure therapy, adaptive servo-ventilation (contraindicated in symptomatic heart failure with LVEF ≤45%), or supplemental oxygen.

Obesity hypoventilation syndrome: BMI ≥30, daytime PaCO2 ≥45 mmHg, and sleep-disordered breathing without other cause; treatment is PAP (often BiPAP) plus weight loss.

Pediatric OSA: adenotonsillectomy is first-line for most children with OSA and adenotonsillar hypertrophy.

Narcolepsy type 1: excessive daytime sleepiness plus cataplexy and/or CSF hypocretin-1 ≤110 pg/mL; type 2 lacks cataplexy and has normal CSF hypocretin.

MSLT criteria for narcolepsy: mean sleep latency ≤8 minutes and ≥2 sleep-onset REM periods (SOREMPs) across 5 naps; a preceding nocturnal SOREMP can substitute for one.

Cataplexy: sudden loss of muscle tone triggered by emotions, typically preserved consciousness; treat with sodium oxybate, pitolisant, or antidepressants.

Idiopathic hypersomnia: excessive daytime sleepiness with MSLT mean sleep latency ≤8 minutes and <2 SOREMPs, or total 24-hour sleep ≥11 hours; no cataplexy.

Kleine-Levin syndrome: recurrent episodes of hypersomnia, hyperphagia, and hypersexuality, often in adolescent males; treatment is supportive, with lithium or stimulants for prevention.

CSF hypocretin-1 ≤110 pg/mL is diagnostic of narcolepsy type 1; levels are normal in narcolepsy type 2 and idiopathic hypersomnia.

Wake-promoting agents for narcolepsy include modafinil, armodafinil, methylphenidate, amphetamines, pitolisant, and solriamfetol; sodium oxybate is for cataplexy and daytime sleepiness.

MSLT must be preceded by adequate sleep (≥6 hours) and actigraphy for ≥1 week to exclude insufficient sleep; stop antidepressants ≥2 weeks before testing when safe.

Obstructive sleep apnea and insufficient sleep syndrome are common causes of secondary hypersomnolence and must be excluded before diagnosing central hypersomnias.

Delayed sleep-wake phase disorder: sleep onset and wake times delayed ≥2 hours relative to desired/required times, with difficulty advancing; common in adolescents.

Advanced sleep-wake phase disorder: sleep onset and wake times advanced, often with early-morning awakening; more common in older adults.

Shift work disorder: insomnia and/or excessive sleepiness temporally associated with work schedule during night or rotating shifts.

Jet lag disorder: sleep disturbance and daytime dysfunction after travel across ≥2 time zones; eastward travel is typically harder to adapt.

Non-24-hour sleep-wake rhythm disorder: circadian period not entrained to 24 hours, most common in totally blind individuals; treat with timed melatonin.

Timed bright light exposure and melatonin are mainstays; for delayed phase, morning bright light and evening melatonin; for advanced phase, evening bright light and morning melatonin.

Melatonin is not FDA-regulated as a drug; typical doses 0.5-3 mg taken 1-3 hours before desired bedtime for phase advance.

Actigraphy with sleep logs for ≥1-2 weeks is the preferred method to assess circadian phase and sleep-wake patterns.

Dim light melatonin onset (DLMO) is a marker of circadian phase; measured in saliva or plasma under dim light conditions.

NREM parasomnias (confusional arousals, sleepwalking, sleep terrors) arise from slow-wave sleep, often in first third of night; patients typically have amnesia for events.

REM sleep behavior disorder (RBD): dream enactment with loss of REM atonia; polysomnography shows REM without atonia; strongly associated with synucleinopathies (Parkinson disease, Lewy body dementia, multiple system atrophy).

RBD treatment: melatonin or clonazepam; ensure bedroom safety; avoid SSRIs/SNRIs and tricyclics which can unmask or worsen RBD.

Sleep terrors: abrupt arousal with scream, autonomic surge, and confusion; usually no recall; common in children and often resolves spontaneously.

Nightmare disorder: repeated dysphoric dreams with awakening and recall; treat with imagery rehearsal therapy; avoid alcohol and sleep deprivation.

Restless legs syndrome (RLS): urge to move legs, worse at rest and evening/night, relieved by movement; diagnosis is clinical; check ferritin and treat if <75-100 ng/mL with iron.

Periodic limb movements of sleep (PLMS): repetitive limb movements (≥4 consecutive, 5-90 s apart) on polysomnography; PLMS index >15/hour in adults is abnormal; not all require treatment.

Sleep-related bruxism: teeth grinding during sleep; may cause dental damage and jaw pain; treat with oral appliance and stress management.

Sleep enuresis: recurrent bedwetting in children ≥5 years; primary enuresis is common and often self-limited; evaluate for secondary causes.

Obstructive sleep apnea is independently associated with hypertension, coronary artery disease, stroke, atrial fibrillation, and type 2 diabetes.

Depression is bidirectionally associated with insomnia; treat both concurrently; CBT-I improves both insomnia and depressive symptoms.

SSRIs, SNRIs, and bupropion can suppress REM sleep; tricyclics and mirtazapine may increase sleep and weight; monitor for RBD unmasking.

Benzodiazepines and opioids increase risk of central sleep apnea and worsen obstructive events; avoid in patients with sleep-disordered breathing.

Chronic obstructive pulmonary disease: nocturnal hypoxemia and hypercapnia; avoid supplemental oxygen that suppresses hypoxic drive without monitoring; noninvasive ventilation for chronic hypercapnia.

Heart failure with reduced ejection fraction and central sleep apnea: adaptive servo-ventilation is contraindicated in symptomatic HFrEF with LVEF ≤45% due to increased mortality.

Chronic pain and fibromyalgia are associated with nonrestorative sleep and alpha intrusions; treat pain and sleep concurrently.

Post-traumatic stress disorder: nightmares and fragmented sleep; imagery rehearsal therapy and prazosin (off-label) may help.

Substance use: alcohol reduces sleep latency but increases wake after sleep onset and suppresses REM; cannabis withdrawal causes insomnia.

Infants: sleep-wake patterns consolidate by 3-6 months; circadian rhythm emerges around 2-3 months; total sleep needs 12-16 hours including naps.

Children: obstructive sleep apnea peaks at ages 2-8 with adenotonsillar hypertrophy; first-line treatment is adenotonsillectomy.

Adolescents: circadian phase delay and reduced sleep duration; school start times later than 8:30 AM improve sleep and academic performance.

Pregnancy: insomnia, restless legs syndrome, and OSA increase; supine sleep position in late pregnancy is associated with stillbirth; screen for OSA and treat.

Older adults: advanced sleep phase, increased awakenings, reduced slow-wave sleep; melatonin secretion decreases; caution with sedative-hypnotics due to falls and cognitive impairment.

Pediatric polysomnography: AHI ≥1/hour may be abnormal in children; scoring rules differ from adults (e.g., hypopnea criteria).

Breastfeeding and postpartum: sleep disruption is common; screen for postpartum depression and insomnia.

Menopause: vasomotor symptoms disrupt sleep; treat with hormone therapy or nonhormonal options; assess for OSA and mood disorders.

Polysomnography (PSG) records EEG, EOG, chin EMG, ECG, airflow, respiratory effort, oxygen saturation, and body position; used for comprehensive sleep assessment.

Home sleep apnea testing (HSAT) is appropriate for adults with high pretest probability of moderate-severe OSA without significant comorbidity; not for children, suspected central apnea, or severe cardiorespiratory disease.

MSLT: 5 naps at 2-hour intervals after nocturnal PSG; measures mean sleep latency and SOREMPs; requires prior adequate sleep and drug washout.

Maintenance of wakefulness test (MWT): measures ability to stay awake in a quiet, dimly lit room; used to assess treatment response in narcolepsy or OSA; mean latency <8 minutes is abnormal.

Actigraphy: wrist-worn device estimating sleep-wake patterns over days to weeks; useful for circadian rhythm disorders, insomnia, and insufficient sleep syndrome.

PSG scoring: sleep onset is first epoch of any sleep stage; REM onset is first epoch of REM; arousal requires abrupt EEG frequency shift ≥3 seconds.

Multiple sleep latency test is contraindicated in children <5 years; interpret with caution in depression and anxiety.

Oximetry alone is not sufficient for OSA diagnosis; it can be a screening tool but has low specificity.

Home sleep apnea testing may underestimate AHI; negative results in high-risk patients warrant PSG.

CBT-I is first-line for chronic insomnia; components include stimulus control, sleep restriction, cognitive restructuring, and relaxation; effective via in-person or digital delivery.

PAP therapy: CPAP for OSA; BiPAP for intolerance or hypoventilation; adaptive servo-ventilation for central sleep apnea (contraindicated in HFrEF with LVEF ≤45%).

PAP adherence: ≥4 hours/night on ≥70% of nights; interventions for poor adherence include mask refitting, humidification, and behavioral support.

Oral appliances: mandibular advancement devices for mild-moderate OSA or PAP intolerance; side effects include dental changes and temporomandibular joint pain.

Hypoglossal nerve stimulation is an option for moderate-severe OSA in PAP-intolerant patients with favorable anatomy and BMI <32-35.

Surgical options: adenotonsillectomy for pediatric OSA; uvulopalatopharyngoplasty, maxillomandibular advancement, and tracheostomy for selected adults.

Weight loss (lifestyle, pharmacotherapy, bariatric surgery) improves OSA and is recommended for overweight/obese patients.

Pharmacologic: modafinil/armodafinil for residual sleepiness in treated OSA; wake-promoting agents for narcolepsy; sodium oxybate for cataplexy; melatonin for circadian disorders.

Positional therapy (avoiding supine sleep) is an option for positional OSA; avoid in patients with severe OSA or comorbidities.