Purpose of a Sleep Study

About Your Visit

You have met with a sleep specialist who has recommended that you undergo a sleep study. What should you expect during your sleep study? Sleep studies, also known as polysomnograms, are used to diagnose sleep disorders. They involve spending the night sleeping at the sleep center. Sleep studies are the best means of understanding how you sleep.

Before Your Visit

Before you arrive for your sleep study in the early evening, there are some important preparations that should be made. The day of your sleep study, you should:

  • Avoid caffeine after lunch,
  • Avoid alcohol,
  • Avoid naps the day of the study, as these may interfere with your ability to sleep,
  • Shower and avoid using hair sprays or gels before you come to your appointment. These products may interfere with the sleep recording.

What to Expect at the Sleep Center

At the Minnesota Regional Sleep Disorders Center, there will be a bed, bathroom facilities, bedroom furniture, a television, and the equipment necessary to complete the study in your room. We also have an additional patient lounge with a phone and television. There will not be any other patients in your room.

Preparing for your sleep study

Bring any items that you need for your nightly routine. Prepare for the sleep study as if you are staying in a hotel for the night. You may want to bring:

  • Comfortable pajamas, 2 piece is preferable, or t-shirt, shorts, sweats, etc.
  • Toothbrush and toothpaste, deodorant, etc.
  • Reading material
  • Clean clothes for the morning
  • You may bring your own pillow, favorite blanket or other items that may help you sleep.

Upon arriving at the sleep center, the sleep technologist will give you a brief tour and ask you to change into your sleepwear.

The technologist will spend about 1 hour setting you up for your sleep study. This time can vary, depending on the complexity of your individual set-up. The technologist will measure the dimensions of your head and mark landmarks on your scalp with a marking pencil. The marks are not permanent and will wash off with soap and water. At designated places, a Q-tip will be used to clean small patches of your skin. This preparation is important to clean off the oils of your skin so that wires can be put in to place for the Electroencephalogram (EEG) and other monitored areas.

The EEG measures your brain wave patterns brain-wave patterns, or electrical activity of the brain. The results of these patterns will help determine the stages of sleep. Some of the wires will be taped in place on the face. There are no needles in modern sleep electrodes, and this preparation should not hurt.

In addition to the electrodes on your face and scalp, there are a few other items that will be applied, including:

  • a flat adhesive sensor on your neck
  • sticky pads on your chest to monitor your heart rhythm
  • stretchy cloth belts that go across the chest and stomach to measure breathing and
  • sticky pads applied to your shins and also possibly to your forearms to monitor movements

All of these wires will be connected to a small box. This box can be carried around, so you will be able to move around the center.

Finally, just before going to bed, a nasal cannula, a plastic tubing that sits at the nose, will be applied. This tubing measures airflow. A probe that measures the amount of oxygen in your blood will also be applied to your finger.

What to do before you go to sleep

After getting set up, you will have some time when you are left alone. It is important to stay awake before starting the study. Most patients bring reading materials or other things to work on. You may bring your computer or device for listening to music with headphones.

Some patients with sleep apnea are likely to need continuous positive airway pressure (CPAP) during the night, so you will be fitted with a mask and practice with this before going to bed. The CPAP will be provided for these patients. If you are already on CPAP you may be asked to bring it in to verify the pressure that it is set at or you may be asked to bring your mask to evaluate for proper fit.

When the sleep study begins

When you feel drowsy enough to fall asleep, you will need to let your technologist know. They will help you into bed and connect the wire box to a computer that will allow the technologist to monitor you from another room. There will be a small infrared camera and two-way speaker in your room. If you need to get up during the night, you will have a call button that will alert the technologist you would like assistance.

Before going to sleep, the technologist will need to test the equipment. You will open and close your eyes, move them around, snore, take breaths in and out and even move your arms and legs. If something goes wrong with a wire, or if one comes loose during the night, your technologist will fix it.

The biggest concern people have is whether they will be able to sleep. Surprisingly, most are able to sleep, even with all the wires and the new environment. It is very rare to have someone not be able to sleep at all.

The morning after your study

You will be awakened after the sleep study data is collected in the morning and be given the opportunity to shower and enjoy a complimentary breakfast.  Further testing is sometimes necessary after an all-night sleep study, but you will be informed by your sleep specialist if that may be a possibility.

What happens after my sleep study?

Some patients may receive results of their studies in the clinic the morning they leave. If you do not receive results, your technologist will clarify with you how you will receive your results.


dr Vargese explaining the purpose of a sleep study in a sleep study room for a patient who will get ready for a sleep study