How does a sleep study work?
A sleep study involves these different sensors because the quality of your sleep can depend on many factors. Using multiple types of sensors, each tracking a specific body system or process, lets healthcare providers take an in-depth look at your sleep. That can make a big difference in diagnosing certain sleep-related conditions.
A sleep study involves the following sensors and monitoring methods:
- Electroencephalography (EEG): These sensors have a sticky, electrically conductive gel coating. The coating helps the sensors stick to your head while they detect and record the electrical activity of your brain, known as brain waves, while you’re asleep. Different wave types happen during different stages of sleep. That’s a key way to identify sleep disorders and issues.
- Electrocardiography (EKG or ECG): During a sleep study, you wear a single EKG sensor on your chest to pick up the electrical activity of your heart. Examining heart activity allows a healthcare provider to see if there’s any issue with your heart’s beating pattern (rhythm) and internal electrical system.
- Electromyogram (EMG): These sensors attach to the skin, usually on your face and a leg, to track muscle movement. Unlike a standard EMG, these sensors are for monitoring only. Unlike a standard diagnostic EMG, the sensors don’t also activate any muscles.
- Electro-oculography (EOG): This test involves placing adhesive sensors on the skin around your eye. These sensors detect eye activity. You’ll wear four of these sensors for a sleep study, two around each eye.
- Breathing sensors: These include sensors that detect air movement through your mouth and nose.
- Respiratory inductive plethysmography (RIP) belt: A RIP belt is a device that detects the expansion of your torso, especially around your chest and belly, when you breathe.
- Pulse oximeter: This is a small adhesive sensor that sticks to the tip of your index finger. It reads your pulse and the level of oxygen in your blood.
- Video and audio monitoring: This allows sleep lab staff and providers to see and hear what’s happening while you sleep. Providers can use this if any of the above sensors give them unusual or concerning readings. The recordings also synchronize with sensor data, so a provider trying to interpret sensor readings can see and hear what was happening at that exact time.
What should I expect before a sleep study? How do I prepare for a sleep study?
A healthcare provider, usually a pulmonologist (a physician specializing in lung and breathing conditions) or a sleep medicine specialist, will recommend a sleep study based on your symptoms and health history. Once they do, they can often provide you with options for sleep labs in your area, and they may even be able to help you directly schedule with a sleep lab.
The scheduled time for your sleep study depends on your regular sleep habits, preferences, schedule and circ*mstances. Providers are most likely to recommend that you schedule your study at a time when you’re normally sleeping. It’s also common that sleep labs can schedule studies for people who sleep overnight or people who work at night and sleep during the day.
Preparing for a sleep study involves packing for an overnight stay and bathing/grooming for a medical procedure. While there might be some variations depending on sleep lab procedures and capabilities, the following are generally helpful to keep in mind while preparing:
- Follow your provider’s guidelines on bathing and grooming. A common recommendation for a sleep study is to bathe or shower beforehand. However, you should avoid using creams, lotions, hair care products, etc., afterward. Clean skin without any additional products on it is best, so the sensors that are part of a sleep study can stay attached and get clear readings. Likewise, hair products such as hair gel or hairspray can make it harder for the adhesive gel on the EEG sensors to stick to your head. You should also avoid using nail polish or fake nails, as these can affect the pulse oximeter readings from your finger.
- Pack like you’re staying the night at a hotel. Bring a toothbrush, pajamas or sleepwear, clothes to wear the morning after your sleep study and any other hygiene or personal grooming items you might need. If you have questions about other items you could need, sleep lab staff or your healthcare provider can provide more information and guidance on what you can expect. Bringing makeup remover is also a good idea if you wear makeup or other cosmetics.
- Take your medications as usual unless your provider says otherwise. Your provider will guide you on which medications to keep taking and which to stop temporarily before your sleep study. If you have any questions about this, be sure to talk to your provider. Stopping some medications suddenly can have unpleasant or dangerous effects. Talking to your provider can help you avoid these before your sleep study.
- Tell your healthcare provider about any skin allergies you have. Some adhesives used with sensors for a sleep study can cause irritation or an allergic skin reaction. Knowing about these allergies in advance can help your provider find alternatives that won’t cause a reaction.
What should I expect on the date of a sleep study?
On the day of your sleep study, you should mostly go about your usual routine. But there are also a few things you should keep in mind (unless your provider tells you otherwise):
- Avoid caffeine and alcohol for at least eight hours before your sleep study. Both can disrupt your normal sleep patterns and affect the results of your sleep study.
- Don’t nap. Taking a nap can make it harder for you to fall asleep during your sleep study.
- Stick to your routine as best you can. The more naturally you sleep during a sleep study, the more accurately a healthcare provider can interpret the results, diagnose any condition(s) you have and treat you accordingly.
What should I expect during a sleep study?
After you arrive at the location where the sleep study is taking place, the healthcare providers who’ll oversee the study will take you to the room where you’ll stay the night. Once there, you’ll change into your sleepwear, and then the staff will go through the process of attaching the sensors to the various places on your body. Most of the sensors either have adhesive on them or need tape to attach them (if you have sensitive skin or adhesive allergies, be sure to tell the staff before they begin attaching the sensors).
After staff attach the sensors, they’ll have you do a few tasks to help them check that the sensors are working and calibrated correctly. The tasks are simple and include moving your eyes, opening/closing your mouth and moving your legs.
The sensor wires should be long enough to allow you to move comfortably in bed. However, if you need to get out of bed, a staff member may need to assist you in unplugging the wires. Don’t unplug them unless a staff member tells you how to do so correctly, or it might affect the sleep study results.
After staff members calibrate the sensors, you can relax and watch TV or read before going to sleep. Most people don’t sleep as well during a sleep study because it’s an unfamiliar environment or because of the sensors they’re wearing. However, this usually won’t impact your study’s results.
While you sleep, providers and personnel monitoring your sleep study may check on you under certain circ*mstances. These include:
- If a wire or sensor comes loose, staff will usually come in, wake you and reattach the sensor.
- If they see signs that you’re having a serious problem during your sleep study, such as a seizure or other potential medical emergency.
What should I expect after a sleep study?
In the morning, you’ll wake up and sleep lab personnel will help disconnect and remove all the sensors. After that, you can change into your clothes for the day and leave the sleep lab.
What are the risks and side effects of a sleep study?
Very few side effects or complications can happen with a sleep study. These are most likely to be irritation from — or a reaction to — adhesives/tapes used to attach sensors. Another common effect is that people don’t sleep as well or for as long because they’re in an unfamiliar place.
There may be other possible complications, but these are uncommon and vary from person to person. A healthcare provider is the best person to tell you more about what’s likely in your case.
