What is measured in polysomnography (PSG)?
Although there are some differences in the ways different labs perform PSG, the main parameters measured are : (i) Eye movements during sleep by electro-oculography (EOG) (ii) Brain rhythms by electro-encephalography (EEG) (iii) Heart rhythms by electrocardiography (EKG) (iv) Movement of body muscles by electromyography (EMG), usually limb muscles. In addition, oxygen levels in blood are recorded continuously by an oxygen monitor (pulse oximeter), and often, audio/video recordings are made for analysis of sleep quality, snoring and movements. Moreover, air flow through the nose is also measured by special flow meters. The data is analyzed by computers and various types of disorders during sleep, including obstructive sleep apnea, can be measured. Do I to stay overnight for a PSG? Yes, you do in most instances. The complexity of the test means that you have to sleep in a laboratory. Only basic sleep pulse oxymetry is possible at home, which is often not capable of making the diagnosis o
