Sleep studies, whose medical name is Polysomnography, are painless and do not translate into a risk for the patient, they are intended to determine the structure of sleep (sleep phases) and the presence of abnormal phenomena, such as apneas (respiratory pauses). , abnormal movements, sleepwalking or others. It monitors brain waves and various other functions of the body while sleeping: breathing, heart rate, respiratory effort, snoring, and oxygen levels. Polysomnography with hospitalization is performed, usually at night, in a specially adapted room in the hospital (Sleep Unit). Electrodes are placed on the patient's chin, scalp, and eyelids, and also on the chest to monitor heart and respiratory rates.