A 90-second segment of our patient’s second polysomnogram. This figure represents a fairly typical 90 seconds of supine NREM stage 2 sleep recorded at 4:00 a.m. of our patient’s second polysomnogram. All the channels are identical to those of the first polysomnogram (refer to the legend of Figure 1). Inspiratory airflow limitation persists in the second polysomnogram evidenced by broad, flattened inspiratory airflow signals throughout the figure (inspiration is down-going), but without audible snoring recorded by microphone (Snoremic; There is one audible snore at the far right of the channel). It is not possible to compare airflow values between studies because the signal cannot be precisely calibrated (the signal depends both upon sensitivity of the amplifier and upon the precise position of the pressure catheter sensing air pressure below our patient’s nose). However, based upon the principals of flow through biological tubes, decreasing nasal resistance by palatal expansion will increase maximal airflow under conditions of inspiratory airflow limitation. Furthermore, the paradoxical thoracoabdominal motion characteristic of increased inspiratory effort observed during the first polysomnogram is no longer present. Compared to Figure 1 with its heart rate of 76 beats/minute and respiratory rate of 19 breaths/minute, this figure demonstrates slowing of the heart rate to 65 beats/minute and the respiratory rate to 16 breaths/minute. The periodic leg movements that were present throughout the first polysomnogram and are evident in Figure 1 (EMGRTA) are absent from this figure.