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What is a Sleep Study?



What is it?

A diagnostic sleep study is called a polysomnogram(PSG). It records your brain waves, heart rate and rhythm, oxygen blood saturation, breathing patterns, eye and leg movements as well as muscle tension. Sensors are placed on your head, face, chest , finger and legs, these senors send electrical signals to a computer located where the technician is.

The brain-wave signals show when you are asleep and awake throughout the night. Both the brain-wave and eye-movement sensors are used to identify when you are in REM (rapid eye movement) sleep. This is a stage of sleep where you have most of your dreams and it is noted by the movement of the eyes from side to side.

The breathing sensors detect low air flow and shows the number of times you have a problem breathing. 

A pulse oximeter clip will also be placed on your finger to mointor your blood oxygen level.

The leg sensor show both minor small and major movements that are made during the night.

This Video Will Walk You Through A Sleep Study

Who has a PSG?

A polysomnogram is often used in the following cases:

  • To diagnose a patient with sleep-related breathing disorders, such as sleep apnea

  • To set the correct levels of continuous positive airway pressure (CPAP) in patients with sleep related breathing disorders

  • To go along with a daytime MSLT to see if someone has narcolepsy

  • To document behaviors during sleep that can be violent or could be harmful to the patient or others

What happens when I have it?

Everyone at our sleep center will do everything possible to make you feel relaxed. You will be asked to come to the center in the evening at either 8:15pm or 9:00pm. We will give you some time to make yourself at home in the bedroom. No other patients will be in the room with you.

You will not feel any pain during the polysomnogram. The sensors are gently placed on your skin and connected to a computer. The wires are long enough to let you move around and turn over in bed. You will be asked make a series of movements to record that the sensors are working.

You are free to read or watch TV until your normal bedtime. Then the lights are turned out and it is time for you to try to fall asleep. A infrared video camera allows a technologist to see you from a nearby room. The tech may have to enter your room if a sensor comes loose. You will have a buzzer to call the tech if you need to go to the bathroom during the night and the tech will detach from the monitoring system so that you go.

Most people have little trouble falling asleep during the study, but not all people sleep as well as they do at home. This doesn't affect the results. In most cases, you only need to sleep a small amount of time to find the source of your problem. The PSG is not a test that you can fail.

In the morning  the sensors will be removed, and you will be free to go. You may be tired if you did not sleep well during the night. Otherwise, you can return to normal activities on the day after a sleep study.