Diagnostic tests are essential for the assessment of many sleep disorders. They are broadly known as ‘sleep studies.

Home Sleep Apnoea Tests: Most cases of obstructive sleep apnoea can be diagnosed by home sleep studies. They vary in complexity.

1. Pulse oximetry: This is a standard test for diagnosing sleep apnoea. This is also known as a ‘Level 1’ sleep study. The pulse oximeter measures pulse rate and blood oxygen saturation. Pulse oximeters used for diagnosis of sleep apnoea are able to record these parameters over several hours. The data is processed by the software which generates a report which is interpreted by the technologist/physician to diagnose sleep apnoea.

2. Cardio-respiratory Polygraphy (‘polygraphy’ or Level 2 sleep study): In addition to pulse rate and oxygen saturation, we measure the respiratory airflow and chest/abdominal wall movements during a Cardio-respiratory Polygraphy. This test is better able to distinguish between obstructive and Central Sleep Apnoea. It also helps to diagnose Positional Obstructive Sleep Apnoea.

3. WatchPAT sleep study:

In addition to pulse rate and oxygen saturation, this test indirectly measures sleep by monitoring the peripheral blood vessel tone.