Sleep study (Polysomnography) 


These studies are used to assess patients with sleep problems especially obstructive sleep apnoea (OSA). Untreated OSA is a potentially serious condition that can cause high blood pressure (hypertension) and other cardiovascular disease, headaches, memory problems and weight gain.


Full polysomnography requires an overnight stay in hospital or a sleep laboratory and is therefore a expensive investigation. The patient is fitted with various devices to record breathing function, body position, abdominal wall muscle movements and blood oxygen levels for a period of several hours. The results are recorded together and analysed on a computer. The number of apnoeic events, when the patient stops breathing for more than 10 seconds, and hypopnoeic events, when airflow is reduced by 50%, are recorded with blood oxygen saturation. These measures allow sleep apnoea to be diagnosed and the severity quantified.

Home sleep studies are a useful, less expensive alternative screening assessment.