Sleep Study (Polysomnography)

What is Sleep Study (Polysomnography)?

Polysomnography used for diagnosing sleep disorders is the most common method for testing sleep apnea condition. PSG is usually conducted at a hospital or a sleep center during the night time. PSG is occasionally conducted during the day to accommodate shift workers. The sleep specialists often use the results of a PSG to determine the future treatment plan for a patient.

During a PSG, the patient’s bodily functions are monitored while the patient sleeps. The most common data recorded during this test are brain waves, blood oxygen levels, heart and breathing rates, and eye movements. PSG also records the shifting patterns between REM sleep stage and non-REM sleep stage. The average patient will experience about 4 to 6 shifting cycles during a whole night of sleep.

PSG can accurately detect the extent of sleep apnea in a patient by carefully monitoring the recording all the possible symptoms of sleep apnea, which may be:

• Snoring patterns and noise
• Breathing patterns and nasal air movements
• Blood pressure and blood oxygen levels
• Drowsiness during the day (narcolepsy)
• Restless sleep
• Sleep-related seizures
• Limb movements
• REM disorders
• Insomnia

Left untreated, sleep apnea can increase the risk for heart disease, high blood pressure, and stroke. The PSG is painless and noninvasive, so the test does not involve any risk. The patient may receive the results of this test after two days.

The Apnea-Hypopnea Index (AHI) indicates the extent of sleep apnea, an example of which is provided below:

• AHI score of 5 to 15 indicates mild sleep apnea
• AHI score of 15 to 30 indicates moderate sleep apnea
• AHI score above 30 indicates severe sleep apnea

The sleep specialist will usually put a lot of stress on the AHI when determining the treatment plan for sleep apnea for a particular patient.