ABFM Sleep Medicine cheat sheet

Obstructive sleep apnea (OSA) diagnosis: apnea-hypopnea index (AHI) ≥5 with symptoms or ≥15 regardless of symptoms on a sleep study.

Central sleep apnea is defined by absent respiratory effort; Cheyne-Stokes respiration with central events is associated with heart failure and reduced ejection fraction.

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

Narcolepsy type 1 requires cataplexy or low CSF hypocretin-1 (≤110 pg/mL); mean sleep latency ≤8 minutes with ≥2 sleep-onset REM periods on MSLT supports diagnosis.

Restless legs syndrome is a clinical diagnosis: urge to move legs, worse at rest/evening, relieved by movement; check ferritin and treat if <75 ng/mL.

Parasomnias: NREM disorders (confusional arousals, sleepwalking, sleep terrors) arise from slow-wave sleep early in the night; REM-related phenomena occur later.

Sleep-related bruxism and rhythmic movement disorder are parasomnias of otherwise healthy sleep; REM sleep behavior disorder warrants neurologic evaluation.

Periodic limb movements of sleep (PLMS) are scored when movements last 0.5-10 seconds and occur in series of ≥4; PLMS alone does not establish a diagnosis.

Sleep-related hypoventilation: PaCO2 >55 mmHg during sleep or ≥10 mmHg rise versus awake value; consider obesity hypoventilation, neuromuscular disease, and COPD.

Insomnia disorder: difficulty initiating/maintaining sleep or early awakening ≥3 nights/week for ≥3 months with daytime impairment despite adequate opportunity.

Cognitive behavioral therapy for insomnia (CBT-I) is first-line; pharmacotherapy is adjunctive and limited-duration.

Depression commonly presents with early morning awakening and shortened REM latency; anxiety with sleep-onset latency.

Obstructive sleep apnea increases risk with obesity, male sex, large neck circumference, retrognathia, and craniofacial abnormalities; STOP-BANG screens risk.

Nocturnal gastroesophageal reflux worsens supine and in the early sleep period; elevate head of bed and avoid late meals.

Nocturia and benign prostatic hyperplasia fragment sleep; nocturnal polyuria is a distinct cause requiring different management.

Chronic pain and fibromyalgia reduce sleep continuity; untreated sleep disturbance amplifies pain perception.

Medications that disturb sleep include SSRIs (REM suppression), beta-blockers (nightmares), corticosteroids, and stimulants; alcohol increases snoring and apnea events.

Asthma has a nocturnal peak (circadian cortisol nadir, vagal tone); nocturnal symptoms suggest poor control.

Shift work disorder: insomnia and/or excessive sleepiness temporally linked to work schedule for ≥3 months; treat with scheduled sleep, light exposure, and cautious stimulant use.

Circadian rhythm sleep-wake disorders include delayed sleep phase (common in adolescents), advanced sleep phase (older adults), and irregular sleep-wake rhythm.

Melatonin is most useful for circadian phase shifting; timing (evening for phase delay, morning for phase advance) determines effect.

Bright light therapy in the morning advances phase; evening light delays phase.

Sleep deprivation impairs glucose tolerance, increases appetite (ghrelin up, leptin down), and raises sympathetic tone - relevant to obesity, diabetes, and hypertension.

Untreated OSA is associated with hypertension, atrial fibrillation, stroke, and increased motor vehicle crash risk.

Sleep loss and circadian misalignment increase risk of mood episodes, particularly mania in bipolar disorder; sleep stabilization is a treatment target.

Drowsy driving: impairment after ~17-19 hours awake approximates a blood alcohol concentration of 0.05%; commercial drivers have regulated rest requirements.

In older adults, circadian amplitude declines; timed light exposure and structured activity improve sleep-wake consolidation.