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What is a polysomnogram?

A polysomnogram is an overnight sleep study that helps healthcare providers diagnose or rule out sleep disorders such as obstructive sleep apnea, periodic limb movement disorder, narcolepsy, restless legs syndrome, insomnia, and nighttime behaviors like sleepwalking and REM sleep behavior disorder (acting out dreams as you sleep).

Often these disorders cannot be identified with a normal office visit – your healthcare provider needs to gather more conclusive evidence while you’re asleep.

Testing at the Knoxville Hospital & Clinics’ Sleep Lab

Sleep studies are performed at the Knoxville Hospital & Clinics’ Sleep Lab.

The noninvasive test records a variety of body functions during sleep – eye and body movements, electrical activity of the brain, breathing patterns, snoring, oxygen levels in your blood, heart rate, and muscle tone.

Listen to our commercial to learn more about the Sleep Lab. Click on the triangular button to start the audio.

Preparing for the sleep study

A sleep study involves an overnight stay at the sleep lab. Our patient rooms are set up to make you as comfortable as possible so you can have a full night’s sleep.

On the day of your in-lab sleep study, you should:

  • Try to follow your regular routine as much as possible.
  • Avoid napping
  • Eliminate use of caffeine after lunch
  • Shower
  • Avoid using hair sprays or gels that can interfere with the sleep recording

If you are on a regular medication, speak with your primary care provider to determine whether any medication should be temporarily discontinued.

When it is time to report for your sleep study, bring any items that you need for your nightly routine. Prepare for the sleep study as if you are staying at a hotel for a night. You may want to bring:

  • Comfortable pajamas or clothes to sleep in
  • A toothbrush, toothpaste and hair brush
  • Makeup remover
  • Reading material
  • Clean clothes for the morning

When you arrive, a sleep technologist will ask about your sleep habits. There may be a pre-sleep questionnaire for you to fill out.

You will have some time to make yourself at home. There will not be any other patients in your room.


Woman sleepingTesting process

When you are ready to go to bed, the sleep technologist will attach sensors to your body. The sensors, which are glued or taped to you, monitor your body while you sleep. These sensors are painless. Make sure to tell the technologist if you are allergic or sensitive to any adhesives.

The wires are long enough to let you move around and turn over in bed. At the start of the test, you will be asked to move your eyes, clench your teeth and move your legs. This will make sure that the sensors are working.

You are free to read or watch TV until your normal bedtime. When it is time for you to try to go to sleep, the lights will go off and a low-light video camera will allow the technologist to see you from a nearby room. If a sensor comes loose or you need to go to the bathroom during the night, the technologist will have to help you with the wires.

Many patients do not sleep as well as they would at home. This may be because of the sensors or the unfamiliar environment. This typically does not affect the results. Nearly everyone falls asleep during an in-lab study. In most cases, you do not need a full eight hours of sleep for the doctor to make a diagnosis. Occasionally, you may be prescribed medication to help you sleep during the in-lab sleep study.

In the morning the technologist will test and then remove the sensors. You may be asked to fill out a morning questionnaire that asks about the quality of your sleep and your experience in the sleep center. The in-lab study is complete once you are awake and the sensors have been removed.

Test results

Once the study is complete, the data is evaluated by a registered polysomnagrapher who will score your sleep study by marking your sleep stages and identifying any events of abnormal breathing or leg movement.

Those findings are then reviewed by medical professionals at CIC Associates, P.C. of Des Moine who specialize in all areas of sleeping disorders and their treatments. They will determine what type of sleep problem you may have and provide treatment recommendations to you and your healthcare provider.

What is the average sleep efficiency? 

We consider 85% as normal and really good sleep efficiency is above 90%. For example: You go to bed at 11 p.m. It takes you 25 minutes to fall asleep, and you wake up 3 times for 5 minutes, 15 minutes and 5 minutes again. You wake for the day at 6 a.m.

Hours of operation

Sleep studies are offered Monday, Tuesday and Wednesday evenings, and other evenings if necessary. Patients must be referred by their healthcare provider to receive a sleep study evaluation.

Patients usually check in at approximately 8 p.m. and leave the following morning by 5 or 6 a.m. If you would like more information on sleep disorders and sleep studies, please call Gary Woodhouse, RRT, at 641-842-1465.