| Levels of sleep monitoring | Type of monitoring device and setting | Parameters measured |
| Level 1 | Attended in-lab polysomnography | Polysomnography including electroencephalogram, electromyogram, electrocardiogram or heart rate, airflow, respiratory effort, and oxygen saturation Additional externally assessed parameters can be included (e.g. blood pressure, oesophageal pressure, transcutaneous CO2 and video surveillance) Investigation performed in the sleep lab under continuous supervision |
| Level 2 | Unattended polysomnography in the hospital/sleep unit or at home | Polysomnography including electroencephalogram, electromyogram, electrocardiogram or heart rate, airflow, respiratory effort, and oxygen saturation Investigation performed without any supervision |
| Level 3 | Polygraphic limited channel recording, mainly modified portable sleep apnoea monitoring | Minimum of four channels including ventilation or airflow (at least two channels to detect respiratory movements or respiratory effort and airflow, heart rate or electrocardiography, and oxygen saturation) |
| Level 4 | Single or two channel device | One or two channels, typically including oxygen saturation or airflow |