Unit
- Polysomnography definition: A comprehensive recording of biophysiological changes that occur during sleep, typically performed overnight in a sleep laboratory. It measures brain waves, eye movements, muscle activity, heart rhythm, and breathing patterns to diagnose sleep disorders such as sleep apnea, narcolepsy, and periodic limb movement disorder.
- Historical development: Sleep technology evolved from early electroencephalography (EEG) recordings in the 1930s, with Rechtschaffen and Kales standardizing sleep stage scoring in 1968. The American Academy of Sleep Medicine (AASM) later updated scoring rules in 2007, creating a consistent framework for clinical practice and research.
- Key milestones: The introduction of continuous positive airway pressure (CPAP) for sleep apnea in the 1980s transformed treatment. The development of portable home sleep testing devices expanded access to diagnostics, while digital PSG systems enabled remote monitoring and automated scoring algorithms.
- Role of the sleep technologist: A skilled professional who positions electrodes, operates recording equipment, monitors patients overnight, and ensures data quality. They work under the supervision of a sleep medicine physician and collaborate with respiratory therapists and nurses in multidisciplinary care.
- Common sleep disorders studied: Obstructive sleep apnea is the most prevalent, followed by central sleep apnea, insomnia, narcolepsy, REM sleep behavior disorder, and restless legs syndrome. Each disorder presents distinctive patterns on PSG that require careful analysis by trained personnel.
- Sleep laboratory environment: Typically consists of individual patient bedrooms with soundproofing, dim lighting, and a separate control room housing the monitoring equipment. The environment must be comfortable to promote natural sleep while allowing continuous observation and intervention if needed.
- Safety considerations: Electrical safety is paramount because multiple sensors are attached to the patient. Equipment must be regularly inspected, and staff must follow infection control protocols. Emergency procedures for seizure, cardiac arrest, or equipment failure are required.
- Scope of practice: Sleep technologists perform electrode application, equipment calibration, patient monitoring, and data collection. They do not diagnose conditions or prescribe treatments; those responsibilities remain with the physician. However, they may make technical adjustments during the study to improve signal quality.
- Electrode placement and signal types: PSG typically records at least 6 channels of EEG, 2 channels of EOG, chin and leg EMG, ECG, and respiratory parameters including airflow, effort, and oxygen saturation. Each signal type provides specific information about sleep stages and physiological events. Proper electrode impedance must be maintained below 5 kOhms for reliable recording.
- Patient preparation and education: Before the study, technologists explain the procedure to reduce anxiety. Patients should avoid caffeine and alcohol on the day of the test. Hair must be clean and free of products. Technologists apply electrodes using conductive paste and tape, ensuring patient comfort throughout the setup process.
- Data quality and artifact recognition: Artifacts from movement, sweating, or loose electrodes can obscure sleep patterns. Technologists must continuously observe waveforms and correct issues such as electrode pops, 60 Hz interference, and muscle tension. Prompt intervention ensures high quality data for accurate scoring and physician interpretation.
Scope of Practice
Role: Sleep Technologist in an Accredited Sleep Lab
Within scope:
- Applying surface electrodes for EEG, EOG, EMG, and ECG according to the international 10-20 system.
- Calibrating and verifying each signal channel before the patient arrives.
- Monitoring the patient throughout the night and correcting artifacts as they occur.
- Documenting technical notes about signal quality and patient behaviors.
- Running CPAP or BiPAP titrations under physician orders.
Outside scope:
- Interpreting PSG data to formulate a medical diagnosis.
- Prescribing CPAP pressure settings without physician authorization.
- Administering sedative medications or performing invasive procedures.
- Modifying treatment plans without consulting the supervising physician.
- Releasing official reports without physician review and signature.
Quick Revision
- Polysomnography records multiple physiologic signals during sleep to diagnose disorders.
- The field advanced from 1968 scoring rules to modern digital systems and home testing.
- Sleep technologists handle technical aspects of recording within defined scope boundaries.
- Safety, infection control, and adherence to professional scope are critical in lab operations.