Bispectral index (BIS) monitor is a neurophysiological monitoring device which continually analyses a patient's electroencephalogram during sedation and general anaesthesia to assess the level of consciousness and depth of anaesthesia. BIS monitoring, whilst performing sleep nasendoscopy (using midazolam and propofol), has helped validate depth of sedation and allowed comparison with levels of sedation of control patients during natural sleep. A prospective study of 30 patients with snoring undergoing sleep nasendoscopy with BIS monitoring was conducted. BIS monitoring was recorded throughout the procedure and assessment of snoring was made at the appropriate level of sedation and snoring. BIS values were compared with control patients. The 30 patients undergoing sleep nasendoscopy had average BIS values ranging from 50.72 to 61.2. Similar results were seen with BIS and oxygen saturation in the control group. BIS monitoring provides an adjunct to the assessment of sleep nasendoscopy in determining the level of sedation required for snoring assessment. Comparable BIS values and oxygen saturation levels were obtained between controls and patients during sedation-induced sleep, thus validating the role of sleep nasendoscopy.