Polysomnogram for
Sleep Apnea Diagnosis and Treatment
Sleep centers use what’s known as polysomnogram to make a continuous record of your sleep. About two dozen small, thin electrodes and other sensors are pasted on specific body sites to take readings during the night.
If your doctor thinks you have a sleep disorder, he will send you to a sleep center for sleep investigations. The most common investigation in a sleep laboratory is polysomnography (PSG).In other words, the polysomnogram is used by sleep doctors and sleep technologists to: - record a person's sleep,
- to diagnose many sleep disorders, including sleep apnea,
- to investigate the differences between normal and abnormal sleep.
To collect all the signals from a sleeping person, the sleep doctors use sophisticated equipment, very expensive, called polysomnogram. This equipment is like a computer, with additional systems, such as:
- an electroencephalogram (EEG) - which records the brain wave activity
- an electrooculogram (EOG) - which records the activity of the eyes
- an electromyogram (EMG) - which records the muscles activity
- an electrocardiogram (ECG) - monitors the heart rate and rhythm.
- body movement detector - the patient will have a couple of electrodes placed on the muscles of the shins, together with a body position sensor around the waist.
During your sleep study, you will also have other equipments which collects signals related to breathing, and records the airflow through the nose and mouth, your oxygen and carbon dioxide levels, and how big is your effort to breathe.
Obviously, all these information about your sleep will be recorded through electrodes and wires placed:
- on your scalp, to track the brain waves
- under your chin to measure fluctuations in muscle tension (with EMG)
- near your eyes, to measure the eye movements
- near your nostrils, to measure the airflow
- on your earlobe or finger, to measure the amount of oxygen in your blood (with the oximeter)
- on your chest, to record the heart rate and rhythm
- on your legs, to record twitches or jerks
- and over your rib muscles or around your rib cage and abdomen, to monitor your breathing
The information from the readings are collected on a single file that can be analyzed as they're recorded and later on. The procedure where the sleep technicians mount the wires on your body is not painful; however, the process sometimes exceed a half-hour time and is annoying.
How is sleep apnea diagnosed with polysomnography? Well, there are a lot of technical stuff to know, and this is the reason why a sleep study is done by professionals. But if you really want to know, you can find here some hints on how a sleep doctor interpret your polysomnogram to find if you have a disrupted sleep.
The sleep fragmentation, or the arousals, is one of the most important side effect of sleep apnea disorder. When EEG shows waking activities for 3 to 14 seconds, then the patient has an arousal. According to the American Academy of Sleep Medicine (AASM), the patient must be asleep for at least 10 continuous seconds before an arousal can be scored. Also, a minimum of 10 continuous seconds of intervening sleep is needed to score a second arousal. If the arousal index, or the number of arousals per hour of sleep, is above 10, then the sleep of the patient can be considered abnormal. 
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