Diagnostic Testing: Polysomnography, Home Sleep Apnea Testing, MSLT/MWT, Actigraphy
Polysomnography
In-laboratory PSG records EEG, EOG, chin EMG, ECG, airflow, respiratory effort, oxygen saturation, body position, and limb EMG. It is the reference standard for OSA, central apnea, narcolepsy workup, parasomnias (especially RBD), and periodic limb movements. Scoring follows standardized rules (AASM): stage per 30-second epoch, with arousal and respiratory event definitions. Know that a negative study does not exclude disease if the night is atypical, and that first-night effect can reduce sleep quality.
Home sleep apnea testing
Home testing uses limited channels (typically airflow, effort, oximetry) and is appropriate for adults with high pretest probability of moderate-to-severe OSA without significant cardiopulmonary comorbidity. It underestimates events when total recording time is used as the denominator and is not appropriate for suspected central apnea, significant heart failure, or children.
MSLT and MWT
The MSLT objectively measures sleepiness with five nap opportunities after a preceding PSG; a mean sleep latency ≤8 minutes with ≥2 SOREMPs supports narcolepsy. The Maintenance of Wakefulness Test measures ability to stay awake; it is used to assess treatment response and fitness for duty, not to diagnose narcolepsy. Both require adequate prior sleep and control of confounders (drugs, untreated OSA, circadian factors).
Actigraphy
Actigraphy uses a wrist-worn device to estimate sleep-wake patterns over days to weeks; it is useful for circadian rhythm disorders, insomnia assessment, and estimating sleep duration before MSLT. It does not measure sleep stages and can misclassify quiet wakefulness as sleep.
Traps
Match the test to the question: PSG for RBD/parasomnia, MSLT for narcolepsy, MWT for fitness, actigraphy for circadian patterns.