A 90-second segment of our patient’s first polysomnogram. This figure represents a fairly typical 90 seconds of supine NREM stage 2 sleep recorded at 4:55 a.m. of our patient’s first polysomnogram. The top three channels (F3M2, C3M2, O1M2) represent electroencephalograms. The channels EyeL & R are electro-oculograms monitoring eye movements. EMGChin is a superficial electromyogram of the face muscles at the chin. Its consistently low amplitude indicates that our patient is in continuous sleep. The electrocardiogram demonstrates a heart rate of 76 beats/minute during the 90-second interval. EMGRTA & LTA are superficial electromyograms of the right and left tibialis anterior muscles. The three episodes of increased activity in the EMGRTA channel, in the absence of arousal from sleep, is evidence of the high frequency of periodic leg movements observed during the study. The lowest channels are monitoring respiration. The airflow channel represents inspiration as a down-going signal. The varying amplitude and duration of inspiration together with the supporting evidence of light snoring during early inspiration detected by a microphone taped to the neck (Snoremic) confirms the presence of mild inspiratory airflow limitation during sleep, a characteristic of both primary snoring and upper airway resistance syndrome. The belts recording respiratory effort (Chest and Abdomen) move paradoxically with respiration (three arrows) also reflecting the increased effort associated with inspiratory airflow limitation. SaO2 is the oxyhemoglobin saturation recorded by a pulse oximeter worn on the finger.