Usually a sleep study is performed in a hospital or sleep center. The study identifies different sleep problems, and is a starting point of treatment once a clinical assessment suggests a sleep disorder. A sleep study consists of two parts, usually. The first part consists of the assessment and the second part is to determine the appropriate levels for those for whom CPAP is the mopst appropriate treatment for Apnea.

A typical study involves the patient arriving at the clinic at 8 or 9 in the evening. After a small amount of paperwork the patient is taken to a room that is fitted like a normal bedroom. The differences are the presence of infrared cameras and microphones. These are put in out of the way places to be non-intrusive. Many of these rooms have television and other furniture to remind the patients of a home setting. The patients are asked to bring their own clothing suitable for sleeping.  

The next step is the connection of the electrodes for the 8 different areas that polysomnography studies. Here is a list of those areas:

· EEG (electroencephalography---brain wave analysis) The EEG or electroencephalogram is a major part of a sleep study. It measures and records four forms of brain wave activity - alpha, beta, delta and theta waves. Alpha waves are usually found during relaxed wakefulness, particularly when your eyes are closed. Theta waves are seen during the lighter sleep stages 1 and 2, while delta waves occur chiefly in deep sleep, the so-called "slow wave sleep" found in sleep stages 3 and 4.

• ECG (electrocardiography---heart rhythm measurement) records heart activities, such as rate and rhythm
• EMG (electromyography---muscle tone, leg moving assessment) records muscle activity such as face twitches, teeth grinding, and leg movements. 
• EOG (electro-oculography---eye movement measurement) records eye movements. This is the test for REM or NonREM sleep.
• Pulse oximetry (continuous oxygen measurement) Records blood oxygen saturation. Oxygen saturation is usually in the range of above 90%.
  
   Thoracic/abdominal expansion (breathing effort measurement) Records breathing depth, apnea and hypopnea events.
  
   Airflow and nasal pressure monitoring Records breath temperature, airflow, apnea and hypopnea events.
  
   Microphone (snoring/sleep talking analysis) Records snoring by placing an electrode on the trachea.

The hook-up is not painful. Electrodes allow for freedom of movement in bed. If the subject needs to urinate one or more times in the night, it is easily arranged without the electrodes having to be removed. The test usually continues until 5:30 or 6am. Depending upon the severity of the condition a device such as CPAP or Bi-PAP might be introduced during the first visit. This is done if there is a severity of Apnea which meets a level for which CPAP or Bi-PAP is a foregone conclusion. The units are able to be controlled remotely and a suitable titration is determined. Otherwise a reading is done by a physician and a determination made. If CPAP or Bi-PAP is determined to be appropriate a second session is when the titration is determined.

If CPAP or Bi-PAP is indicated then we have included a list of a number of manufacturers of CPAP or Bi-PAP machines.