Doctors Answers (3)
A Polysomnogram or sleep study is monitoring EEG (brain activity), EMG (muscle movement), ECG(heart rhythm), Oximetry, Respiratory effort, and airflow. Electrodes will be adhered to your head/body along with belts around your abdomen and thorax. There will also be sensors placed in your nostrils. The test is run for a minimum of six hours and ideally you would be sleeping for this duration.
During a sleep study several parameters are measured. These measurements are made through electrodes pasted to various parts of the body and through observation by a sleep technician, either directly or, if ordered, through a video camera. Electroencephalgraphy (EEG) brain waves to determine the stage of sleep or wakefulness. Electromyography (EMG) to measure muscle activity in the chin and the legs. This is to also help with measuring sleep staging and to measure leg movements. Electro-oculogram (EOG). This measures eye movements. During REM (Rapid Eye Movement) sleep, for example, the eye movements are very rapid. During other stages of sleep the movements are slow rolling. Electrocardiogram (ECG). This measures heart rate and monitors for abnormal rhythms. In addition, there are measurements of airflow, snoring, chest movements with inspiration and expiration. The position of the body is monitored. The arterial oxygen level is measured with a device attached to your finger. Sometimes the carbon dioxide level is measured. If you have unusual movement like sleep walking or seizures, the video camera may be turned on to record the event for the doctor to review the next day. A sleep study lasts all night, usually 7 hours. It is painless and rarely does someone not sleep during the test. If you don't sleep well at home you may best take a sleep aide prescribed by your physician. Most sleep aides do not interfere with the sleep test. Not sleeping is what would interfere the most. It is not very helpful to watch someone not sleep all night.
There are no other tests required prior to a sleep study. During the sleep study, the parameters that are typically monitored are: brain waves to determine sleep stages and wakefulness, muscle activity related to your chin and legs, heart rate and rhythm, breathing or lack of breathing through your nose and/or mouth, effort of chest and abdomen while breathing, the constant level of oxygen saturation and if needed CPAP. These things tell us for example if you are indeed have sleep related breathing events and if they cause sleep disruption and/or oxygen loss. The CPAP would be used if indicated and the lowest therapeutic pressure to fix your problem would be determined during the study by the technician/nurse and validated by the Board Certified Sleep Physician.
