 The SensAwakeTM modification to the Fisher and Paykel automatically titrating positive airway pressure APAP device aims to sense whether the patient is awake via respiratory patterns that differentiate between sleep and wake. Upon sensing that the patient is awake the device is able to reduce positive airway pressure PAP aiming to improve patient comfort which should result in more consolidated sleep. This study will investigate Obstructive Sleep Apnea OSA and a automatically Adjusting Positive Airway Pressure APAP device with new technology called SensAwakeTM. This requires experimental confirmation in a randomised controlled trial. Doubleblind randomised crossover trial comparing WASO on standard APAP with WASO using APAP modified by the addition of the SensAwakeTM modification on consecutive nights in participants with moderatetosevere OSA. 