Sleep Apnea Test: How Long Does It Take?

Sleep apnea is a common sleep disorder that affects millions of people worldwide. Those who suspect they may have this condition can opt for a sleep apnea test, also known as a polysomnogram (PSG), to confirm the diagnosis. This test can be done in a sleep disorder centre or hospital, or even at home, depending on the patient's preferences and convenience. The test typically involves spending a night at the chosen facility, where electrodes and other equipment are used to monitor brain and body activity while the patient sleeps. The results of this test can help determine the presence and severity of sleep apnea and guide further treatment options.

In-lab sleep study

An in-lab sleep study, also known as a polysomnography or polysomnogram, is a test used to help diagnose sleep apnea, restless leg syndrome, and other sleep disorders. It involves spending the night at a hospital sleep laboratory or an outpatient sleep clinic, where electrodes and other equipment are attached to your body to monitor your brain waves, breathing, and movement while you sleep.

Before the In-Lab Sleep Study

On the day of your in-lab sleep study, you should follow your regular diet and daily routine, with a few exceptions. It is recommended to avoid caffeine and alcohol after lunchtime, as they can interfere with your sleep and the test results. You should also refrain from taking naps during the day and, if instructed by your healthcare provider, stop taking any regular medications. It is important to check with the sleep centre for any special restrictions or instructions. In terms of what to bring, you should pack similar items as you would for an overnight stay at a hotel, including comfortable sleepwear, slippers or non-skid socks, a bedtime snack, and a book or other reading material if it is part of your nighttime routine.

During the In-Lab Sleep Study

When you arrive at the sleep centre or hospital, you will be assigned to a private bedroom near a central monitoring area where technicians will observe you and other sleeping patients. You will have your own bathroom, and you can inform the technicians when you need to use it so they can detach the wires connecting you to the monitoring equipment. The setup process for the sleep study can take around 45 to 60 minutes, and sometimes even longer for certain types of studies. Electrodes will be placed on your face and scalp to record electrical signals generated by your brain and muscle activity. Additionally, belts will be placed around your chest and abdomen to measure your breathing, and a bandage-like oximeter probe on your finger will measure the oxygen levels in your blood. Other equipment that may be used during the study includes a microphone to record snoring, sticky pads on your chest to monitor heart rhythm, stretchy cloth belts to measure breathing, and an electro-oculogram to record eye movements.

After the In-Lab Sleep Study

In the morning, the technicians will remove the sensors and you can resume your regular activities. The data collected during the study will be analysed by a qualified sleep specialist, and the results will be sent to your doctor. This process can take some time due to the large volume of data, and you will then meet with your doctor to discuss the findings and any necessary next steps.

Polysomnography

In addition to diagnosing sleep apnea, polysomnography can also be used to diagnose other sleep disorders such as periodic limb movement disorder, REM behavior disorder, and epilepsy. It is considered a safe and painless procedure that examines the natural functions of the human body without any radiation or electrical signals sent to the body.

Home Sleep Test (HST)

A Home Sleep Test (HST) is an overnight sleep study conducted in the patient's home. HSTs are used to diagnose sleep apnea, specifically Obstructive Sleep Apnea (OSA), and can be provided by local sleep centres, national sleep testing providers, and hospital-based centres.

HSTs are a good fit for patients who are highly likely to have moderate to severe OSA and have no other significant medical conditions. They are also suitable for patients who are unable to attend an in-lab study or who were unable to sleep during an in-lab study. HSTs are not recommended for patients with a BMI greater than or equal to 45, certain pulmonary diseases, neuromuscular diseases, or congestive heart failure.

The HST device will be mailed to the patient with detailed instructions on how to use the device and activate the recording. The device will record a number of bioelectric parameters during sleep, including breathing patterns, blood oxygen saturation, heart rhythms, and respiratory effort. The patient will then send the device back to their provider for testing and analysis. Results are typically available within 10-14 days and will be interpreted by a board-certified sleep physician who will also provide treatment recommendations.

Sleep study preparation

Sleep studies are typically done overnight, either at a hospital sleep laboratory, an outpatient sleep clinic, or at home. If you're doing an in-lab sleep study, you'll need to check into the hospital or medical center sleep lab for a night of monitored sleep. If you opt for a home sleep test, you'll be sent a kit with a portable sleep data monitor, chest strap, heart rate sensor, and a nasal cannula. You'll set up and administer the test yourself at home.

Before the Study

• Avoid caffeine and alcohol after lunchtime on the day of the test.
• Refrain from taking any naps during the day.
• Wash your hair to remove any hair gel or styling products, as these can interfere with monitoring equipment.
• Check with your sleep center to see if they have any special restrictions or requirements.
• Pack comfortable sleepwear, slippers or non-skid socks, clothes for the next day, your favourite pillow or blanket, a bedtime snack, and something to read if it's part of your routine. You may also want to bring breakfast, as coffee or juice may be provided, but food typically isn't.
• If you take regular medication, consult your doctor to see if you should continue taking it as usual or stop before the test.

During the Study

• When you arrive at the sleep center, you'll need to fill out paperwork and may need to present your health insurance card and/or co-pay.
• A sleep technician will take you to your bedroom for the night and show you where you can put your things.
• You'll have time to change into your sleepwear and go through your regular nighttime routine.
• The technician will set up the equipment and prepare you for the various tests, including marking spots on your scalp and face for the electrodes.
• The technician will help you into bed and connect the wire box to a computer so they can monitor you from another room.
• Try to relax and follow your regular bedtime routine as much as possible.
• If you're unable to fall asleep, don't worry—your healthcare provider may offer medication to help you along, or the testing can be repeated to ensure valid results.

After the Study

• In the morning, the technicians will remove the sensors, and you can go back to your regular activities.
• It will take some time for the sleep specialist to review the data from the study and send the results to your doctor.
• Once your doctor has reviewed the results, they will meet with you to discuss the findings and next steps.

Sleep study results

The results of a sleep study will offer insights into various aspects of your sleep, providing a comprehensive overview of your sleep quality. Here's what the results might include:

• Sleep efficiency: This is calculated by dividing the total number of minutes slept by the total amount of time spent in bed. It provides a percentage that indicates the proportion of sleep time versus awake time.
• Apnea Hypopnea Index (AHI): The AHI assesses the frequency of sleep apnea and hypopnea episodes. A diagnosis of sleep apnea is typically made when five or more episodes occur.
• Oxygen Desaturation Index (ODI): The ODI measures the number of times your oxygen levels drop during sleep, indicating potential sleep-disordered breathing. Normal oxygen levels are considered above 90%.
• Heart rate: Your heart rate during sleep is an important indicator of cardiovascular health. A typical heart rate range is between 60 and 100 beats per minute (BPM). Deviations from this range, either higher or lower, can be indicative of an underlying condition.
• Sleep stages: A sleep study can determine how much time you spend in each sleep stage, including REM sleep and non-REM sleep (stages 1, 2, 3, and 4).
• Breathing patterns: The test will reveal any unusual breathing patterns, such as pauses or absence of breathing, and evaluate the effort required to breathe.
• Blood oxygen levels: By monitoring blood oxygen saturation, the test can identify any desaturation events that may be indicative of sleep apnea or other respiratory issues.
• Body movements: Sensors will track your body's movements, including leg movements, which can be indicative of restless leg syndrome or periodic limb movement disorder.
• Brain activity: Electrodes will record brainwave activity, which can help identify any unusual patterns or sleep disorders like narcolepsy.

Once the results are ready, a qualified healthcare provider will discuss them with you and recommend potential treatment options or further tests if needed. It is important to remember that sleep disorders can have serious health implications, so seeking professional guidance is crucial.

Frequently asked questions