The aim of this research study was to identify an alternative to nasal airflow as a prompt and unobtrusive indicator of sleep apnoea events. This study attempted to select pulse oximetry (SpO2) level as an alternative parameter to indicate the occurrence of sleep apnoea. Ten subjects diagnosed with sleep apnoea underwent an overnight polysomnography (PSG) study. Signals of nasal flow and SpO2 level were recorded. Time differences were compared between the “onset of nasal airflow cessation” (ONAC) and the “onset of three percent oxygen desaturation from the baseline” (OOD) during sleep apnoea events. The results of this study showed that measuring SpO2 level was more comfortable for patients, but that there was around a twenty second delay after the onset of the cessation of nasal airflow. It was concluded that the measurement of SpO2 level was useful for screening suspected sleep apnoea patients, but it might not be able to provide “online detection” of the occurrence of sleep apnoea events.