Overnight Sleep Study: What to expect

Overnight Sleep Study: What to expect

Why is an overnight sleep study so valuable?

Sleep is not a simple process. Many parts of the brain control your sleep in various stages. The stages of sleep include drowsiness, twilight zone/light sleep, deep sleep, and dream sleep.

An overnight sleep study is the best way to analyse your sleep through all of its stages. This kind of study is called a polysomnogram. It measures your brain waves, heart rate, and breathing. It also records movements of your eyes and legs. This will help give your sleep study technician the "big picture" in regards to your sleep pattern. At the same time, it provides precise facts on what your body is doing at every moment of sleep. It really is the best of both perspectives – a panoramic view, but with microscopic details. It is the most complete and scientific way to evaluate your sleep and discover any problems.

At the moment the overnight sleep study is only available at our Morningside branch in Gauteng.

Preparing for an overnight sleep study:

  • Do not have any caffeine in the afternoon or evening before an overnight sleep study. This includes coffee, tea, cola and chocolate.
  • Also avoid drinking any alcohol. You do not want any substance to affect your sleep.
  • Try not to take any naps that day.
  • Before going to the sleep centre in Morningside, wash your hair with shampoo only. After drying your hair, don’t apply any hair spray, oils or gels as they could interfere with the sensors that are attached to your scalp during the study.
  • Pack an overnight bag and include the same items you would take for a stay at a hotel.
  • Bring your medications if you will need to take them while you are away from home. Please be sure to inform the sleep physician of any chronic medication that you are taking.
  • If you have special needs or concerns, tell the sleep centre staff ahead of time.

How does it work?

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. This is a painless process.

The sensors measure the following:

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 all the sensors are working.

You are free to read or watch TV until your normal bedtime. When it is time for you 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.

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 centre. The in-lab study is complete once you are awake and the sensors have been removed.

If you are in any way uncomfortable with an “in-house” sleep study, we have the option for you to complete your sleep study at home. In this case, you will have your electrodes attached at the Renewal Institute branch nearest to you and simply sleep with the device attached at your own home. The device will be removed the next morning and you must return it to the branch for the sleep technician to analyse the data collected overnight.


Members of the sleep team will review and evaluate the information gathered during the sleep study. It may take several days to two weeks to fully evaluate.

A sleep technologist will first score your sleep study by marking your sleep stages and identifying any events of abnormal breathing or leg movement. The sleep physician will then review the results to determine what kind of sleep problem you may have; makes their diagnosis and then contact you to discuss the results and the sleep study report in a follow up consultation.

In summary:

A sleep study is a reliable, scientific, and painless way to find out why you don't sleep as well as you would like. It gives you valuable insight into the process of how you sleep and, with the results, a sleep specialist can develop a treatment plan to help improve the quality of your rest.

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