Polysomnography, a sleep study performed overnight while being continuously monitored by a credentialed technologist, is a comprehensive recording of the biophysiological changes that occur during sleep. It is usually performed at night, when most people sleep, though some labs can accommodate shift workers and people with circadian rhythm sleep disorders and do the test at other times of the day. Labtech Polysomnograph Trainer is designed to demonstrate the operation, theory, repair and servicing of polysomnograph equipment that used at clinics & hospitals. The unit is given the fault diagnosis so as to facilitate the teaching of trouble shooting techniques. A fault simulator is provided with circuit block diagram of the device for the students to study theoretically and experimentally in order to understand the operation of the device.