Q&A: What to Expect During a Sleep Study

Your doctor is concerned about the quality of your sleep, so they have ordered a sleep study to learn more about what goes on when your eyes close at night.

But the thought of going to an unfamiliar laboratory, getting wires attached to your head and body, then having someone watch you try to sleep all night can be intimidating.

We asked UNC Health pulmonologist and sleep medicine physician Adnan Pervez, MD, medical director of the UNC Rex Sleep Disorders Center, to explain what a patient can expect during a sleep study.

What is a sleep study?

A sleep study allows sleep experts to monitor your sleep and collect data from instruments that measure what is going on in your brain and body. The information allows your doctor to diagnose sleep disorders and plan treatment to help improve your sleep. Most sleep studies take place overnight, but they can be done during the day for people who work night shifts.

Sleep apnea is one of the most common diagnoses revealed by a sleep study. There are other conditions, too, such as seizures during sleep or leg movements that can disturb sleep. Sometimes people have changes in the way their heart or lungs function during sleep that their heart doctor or lung doctor may want to know more about.

How do I prepare for a sleep study?

Try not to do anything the night and day before the test that might interfere with getting a good night’s sleep, Dr. Pervez says.

Don’t take a nap or sleep late the day of your sleep study. Avoid caffeine after noon and don’t drink alcohol. You won’t want to exercise close to the time you are due at the sleep lab.

You should bathe before you come to the lab, including washing your hair. After your shower or bath, don’t put on any makeup or lotions. They might interfere with sleep study equipment.

Bring anything you may need to help you sleep better, including pajamas. You may want to bring your own pillow and a book, if you usually read before bed. You can bring snacks, beverages (nonalcoholic and non-caffeinated) and medicines you take at bedtime or first thing in the morning. Remember mouth guards or retainers you usually sleep with.

People younger than 18 or those who need special assistance may bring one adult with them.

Where do I go for a sleep study?

Sleep labs can be in hospitals, medical office buildings, free-standing facilities or hotels. Most sleep studies are considered outpatient procedures.

Typically, you will arrive in the evening, usually around 8 p.m. Depending on the location, you may need to register at a reception area, ring a bell or call a posted phone number to be admitted. The lab will send you directions in advance. Someone will check you in and verify your identification and insurance information. They will likely review information about your health, medications, habits and sleep history.

Once you are checked in, you will be shown to your assigned room for the sleep study. Typically, the room has a bed, side table, closet and private bathroom. Usually there is a television. There is only one patient to a room.

Who does the sleep study?

A sleep technologist is the medical professional who conducts the sleep study. Your doctor or a sleep medicine physician will interpret the results and contact you with a diagnosis and treatment plan. Your doctor will usually not be present for the sleep study.

The sleep technologist will give you time to get settled in your room and put on your sleepwear or a hospital gown. When you are ready, the technologist will set up the equipment. You will sit in a chair or on the side of the bed while the sleep technologist attaches wires (also called leads) to your head, face, chest and arms using a medical-grade adhesive. Belts will be placed around your chest and belly. An oxygen sensor will be placed on your finger and a cannula will be placed in your nose to measure air flow.

The various wires all connect to a unit in the room, usually at the bedside. They measure your sleep stages including cycles of light, deep and REM sleep, plus electrical activity in your brain and muscles, eye movements, heart rhythm and electrical activity, breathing, and the amount of oxygen and carbon dioxide in your blood.

“It takes about half an hour to get everything set up,” Dr. Pervez says.

There is a small camera in the room, similar to a home security camera. While you sleep, your sleep technologist is in a control room in another part of the sleep lab, monitoring how you are sleeping. If any adjustments are needed to the equipment, the sleep technologist may quietly enter the room to perform them. If at any point you require assistance, you can simply call out and the technologist will come help you.

Will I be able to sleep with all those wires and belts attached to me?

Your sleep technologist will help you get as comfortable as possible. The wires are short enough that it is unlikely for them to get tangled, and they detach from the box as one unit if you need to get up during the night to go to the bathroom. The sleep technologist will assist you by disconnecting and reconnecting the equipment.

“We understand it’s not normal to sleep like that, but we try to make patients as comfortable as possible,” Dr. Pervez says. “We would anticipate that some people have difficulty. But by and large, people are able to get enough sleep for us to assess their sleep problems.”

Are there different types of sleep studies?

Different types of sleep studies are available, depending on the reason your doctor ordered the study.

A diagnostic sleep test records what is going on while you sleep. If your symptoms are mild, it may take all night to collect enough data to make a diagnosis.

Sometimes, a patient exhibits clear signs of severe sleep apnea early in the night. If this happens, the sleep technologist may help the patient put on a mask that is attached to a machine that provides positive airway pressure (PAP). Different modes of PAP therapy are available and may be applied depending on your needs, the most common being continuous positive airway pressure (CPAP). The lab will typically have a variety of masks available, and the sleep technologist will help you select the most suitable and comfortable one. Once your mask has been fitted, you go back to sleep and your sleep technician will adjust (titrate) the level of air pressure to best help you breathe while you sleep.

If the sleep technologist is able to get enough diagnostic information, fit the mask and optimally adjust a PAP machine in the same night, that’s called a split-night study. Sometimes, a second night is needed to adjust the PAP machine.

What happens the morning after a sleep study?

If you’re not already awake, your sleep technologist will awaken you in the morning (usually at 6 or 6:30 a.m.) and remove the equipment. You can clean up, shower if you want and get dressed at the lab. Then you are free to leave.

The data collected during the night is compiled and reviewed by sleep technologists, a process called scoring. The prepared data is then sent to a sleep physician for interpretation. This doctor shares the information with the provider who ordered your sleep test, who will contact you with results and recommendations.

Can I do a sleep test at home?

Home sleep tests are increasingly common, especially since the COVID-19 pandemic. They do not collect as much information as a study in a sleep lab, but they are adequate for some sleep disorders, Dr. Pervez says.

“Not every patient requires a lab study,” he says. “If there is a high suspicion of moderate to severe sleep apnea, a home sleep study may be enough to make the diagnosis. If it is inconclusive, a lab study can be performed.”

Most home tests will measure heart rate, oxygen saturation, respiratory effort (how hard you are breathing) and airflow through the nose.

Generally, the patient goes to a sleep lab or doctor’s office during the day to pick up the home equipment, which is about the size of a tissue box. They are shown how to use it and will put it on themselves when they are ready for bed that night. The next day, they take the box back to the lab or office. The data collected overnight is sent to a doctor for interpretation.

PAP therapy typically can’t be applied during a home test. If the home test shows severe problems with breathing at night, the doctor may recommend a titration study in the sleep lab to determine the appropriate settings for a PAP machine.

Whatever the reason for your test, Dr. Pervez encourages patients to try to be open to the process. The purpose is to find out what you need to get better sleep, which leads to better health.

“Overall, I think, people are more afraid to sleep in the lab than they need to be,” he says.

Talk to your doctor if you are concerned about your ability to sleep well, or find a doctor near you.