Generating a Signal: Biopotentials, Amplifiers, and Filters

Understanding the underlying science of the generation of electrophysiologic signals is necessary to monitor and interpret sleep studies accurately. There are many factors that can alter a signal observed on a polysomnogram. Armed with the knowledge of how an electrophysiologic signal is generated and recorded, those who study sleep and its disorders are expected to be able to separate true from artifactual signals, and know the difference between accurate signal data and unexpected alterations in these signals. At any step in the process the diagnostic accuracy of a polysomnogram may be altered or unreliable, which, if not detected and corrected, could adversely affect the care of the patient.