The polysomnography is a noninvasive and painless test that allows the study of sleep, stages (REM and non- REM ) and its various alterations. This indicated to diagnose possible disorders such as obstructive sleep apnea, narcolepsy, excessive sleepiness, restless leg syndrome or night terrors, among others. Overall the night polysomnography performed in specialized centers or at home, and while the patient sleeps, placing electrodes on the chin, scalp and the outer edge of the eyelids apart monitor chest. The system records different variables: blood pressure, the electroencephalographic activity, eye, muscle, heart and breathing. Furthermore, measures the time it takes the patient to fall asleep and duration of the different phases of sleep. A specialist observes from another room, the person being tested while sleeping and polygraph records and stores the information of different physiological signals, which then will be interpreted to make a diagnosis. The period of sleep could also videotaped for later analysis.