Sleep Study
A Sleep Study (polysomnography) is a comprehensive diagnostic neuro-physiological assessment that continuously records biophysical changes across brainwaves, eye movements, muscle activity, and respiration during sleep to identify and stage sleep disorders.
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Polysomnography (PSG): The Gold Standard in Sleep Architecture Telemetry
Polysomnography (PSG) is the definitive diagnostic procedure in sleep medicine. Conducted in accredited sleep centers under the direct supervision of registered polysomnographic technologists (RPSGT), an overnight sleep study captures high-density physiological signals across multiple biological systems simultaneously.
The standard PSG montage incorporates electroencephalography (EEG) electrodes placed along the 10–20 international system (frontal, central, and occipital derivations) to identify brainwave frequencies (delta, theta, alpha, and beta spindles) for sleep staging. Electrooculography (EOG) tracks vertical and horizontal eye movements to identify REM onset, while electromyography (EMG) sensors on the chin and anterior tibialis muscles monitor muscle tone atonia and leg movements.
Simultaneously, respiratory function is monitored using dual modalities: an oronasal thermal sensor for detecting apnea airflow cessations and a nasal pressure transducer for identifying hypopneic airflow reductions. Calibrated respiratory inductance plethysmography (RIP) belts quantify ribcage and abdominal effort, while continuous pulse oximetry and single-lead electrocardiography (ECG) track oxygen saturation and cardiac arrhythmias.
| Physiological System | Sensor Hardware & Placement | Clinical Metric Monitored |
|---|---|---|
| Neuro-Electrical (EEG) | Gold-cup electrodes at F4-M1, C4-M1, O2-M1 | Sleep stage classification: N1, N2 (spindles/K-complexes), N3 (slow-wave), and REM. |
| Ocular Movement (EOG) | Electrodes placed 1cm above/below outer canthi | Differentiates slow rolling eye movements (drowsiness) from phasic rapid eye movements (REM). |
| Submental Muscle Tone (EMG) | Electrodes placed on submental chin muscle | Confirms motor atonia during REM sleep; detects loss of atonia in REM sleep behavior disorder. |
| Respiratory Airflow | Oronasal thermistor & nasal pressure cannula | Detects complete airway cessation (apneas) and partial airflow reductions (hypopneas). |
| Thoracoabdominal Effort | Dual inductive plethysmography (RIP) belts | Distinguishes obstructive effort against collapse from absent central respiratory effort. |
Topic Directory & Specialized Clusters
Preparation, Types & Procedures
Frequently Asked Questions About Sleep Study
Will I be able to sleep with all the sleep study wires attached?
Most patients sleep adequately during a sleep study; sleep technologists ensure sensors are comfortably secured, and clinicians only need approximately 2 to 4 hours of recorded sleep data to reach an accurate diagnosis.
What should I avoid before having a sleep study?
Avoid caffeine, alcohol, daytime naps, sedatives (unless directed by your doctor), and hair products/gels that can interfere with EEG electrode adhesion on the scalp.
What is a split-night sleep study?
A split-night study conducts standard diagnostic monitoring during the first half of the night; if severe obstructive sleep apnea is confirmed, the technologist spends the second half titrating CPAP therapy.