Patients with obstructive sleep apnea (OSA) could have several anatomical causes of obstruction. A sleep endoscopy study is a technique to help determine the anatomical cause of OSA. This study will be using standard of care practice and infuse dexmedetomidine (DEX) to induce sleep. The goals of the study are to (1) confirm airway obstruction with endoscopic view and correlate that with Acoustic Respiratory Rate (RRa) signal at the moment of airway obstruction, and (2) characterize the EEG signals when subjects are under DEX sedation alone.

Inclusion Criteria:

• Adult patients more than 18 years old with American Society of Anesthesiologists (ASA) classification of I, II, or III.
• Patients undergoing sedation for sleep endoscopy with DEX alone, and possible surgical follow-up.

Exclusion Criteria:

• ASA classification higher than III.
• Any deformities or diseases that may prevent application of SedLine (Masimo Sedation Monitoring) or RAM (Masimo Rainbow Acoustic Monitoring) sensors with a proper fit
• Inability to obtain any physiological, vital, demographics and real time anaesthesia data
• Subjects who have known intolerance to any of the drugs to be used according to the study protocol
• Subjects deemed not suitable for study at the discretion of the Principal Investigator.

During the data collection period, which could of lasted up to 8 hours.