Sleep studies support doctors in diagnosing sleep disorders such as insomnia, narcolepsy or sleep apnea and set the starting point for proper follow up. sleep stages are commonly assessed using the physiological criteria based on Electroencephalogram (EEG), Electro-oculogram (EOG), Electromyogram (EMG), heart rate,snoring, and respiration.Holland, Dement, and Raynal in 1974, proposed the term Polysomnography (PSG) for describing the recording, analysis and interpretation of multiple, simultaneous physiologic parameters recorded during sleep.This paper is organized as follows.