Fig. 1.

Evaluation of mouth status. The subject's face was monitored via a video camera. The image in the left (A) showed his mouth was closed. On the polysomnogram, airflow signals were detected both from the (one branch above-the-mouth) thermistor (black arrow) and from nasal airflow sensors in nasal cannulas (white arrow). For the same subjects with mouth open during sleep (B), oral airflow signals detected by the thermistor (black arrow) were preserved, but no nasal airflow signals were seen (white arrow).