A battery-powered device assembly intended to continuously measure and record patient physiological parameters (e.g., arterial oxygen saturation level, pulse rate, respiration effort/pattern, airflow waveform) during sleep in the home, to facilitate the diagnosis of sleep apnoea [e.g., obstructive sleep apnoea (OSA)]. It includes primary components such as sensors (e.g., air pressure sensor) and/or a control unit which may have some user-interface functionality, and typically additional devices which may include a gas sampling face mask and/or connecting leads/cables; collected data is transferred to a central database or computerized device.