So you’ve tried adjusting your bedroom environment and tweaked your sleep hygiene regimen. What now? If you’ve been tossing and turning with sleep problems for a while, your doctor may recommend a sleep study, or polysomnography, to help answer your questions about your sleep quality and enable your doctor to give you a diagnosis.
Historically, most sleep studies have required you to spend the night in a sleep clinic so that your health care team can use special equipment to monitor your brain and body activity as you sleep. But new technology has emerged that allows some people to undergo sleep studies or smaller sleep tests from their own bed.
No matter where you do your sleep study, the test itself is not invasive. “We always tell people nothing is uncomfortable, nothing’s embarrassing, you can wear whatever you want to wear, and pretty much bring whatever you want to bring,” says sleep neurologist and Sleep.com advisor Dr. Chris Winter.
The equipment uses noninvasive sensors that adhere to your skin or hair or are gently placed on your finger to monitor your body. Electroencephalogram (EEG) sensors and other monitors typically track brain and body movements, including your sleep cycles (and the amount of time you spend in each stage of sleep) as well as breathing rate, eye movement, oxygenation, and other metrics. Here’s what exactly you and your doctor can learn from the results of a sleep study and how to prepare for one.
What is a sleep study?
The in-lab study takes place overnight in an exam room that will resemble a hotel room.
You will often arrive for your test in the evening and stay the whole night. However, if you usually work an overnight shift and sleep in the daytime, the test can often be scheduled during your normal sleep hours.
Types of sleep studies
There are several different sleep studies that measure different elements of your brain and body as you sleep.
In-lab sleep study
This type of polysomnography happens overnight in a sleep clinic. While you’re under observation, a team gauges sleep quality and measures your body’s vital signs while you’re sleeping, including your:
- Blood oxygen levels
- Eye movements
- Activity in your muscles and brain
- Breathing
- Snoring
- Heart rate
CPAP titration
People diagnosed with sleep apnea often use a continuous positive airway pressure (CPAP) machine to manage their symptoms. If your doctor thinks this machine could help you, they might have you do a CPAP titration. This test helps determine how much air pressure your machine needs.
If your doctor is able to determine that you have sleep apnea during the first half of the in-lab sleep study, they may be able to do the titration during the second half (known as a split-night study). If not, you may have to do a second in-lab sleep study.
Home sleep apnea test
Like the name suggests, this test doesn’t happen in a sleep clinic. This study measures your breathing while you sleep at home in your own bed. However, it can’t provide as much information as an in-lab test, and it isn’t overseen by a health care professional.
If your doctor orders this test, they will provide you with a device to wear while you sleep. Depending on the maker of the test, this device may attach to your head, abdomen, or arms.
While you sleep, the test will measure your:
- Blood oxygen levels
- Heartbeat
- Breathing effort
- Snoring
At-home studies are often significantly cheaper than an in-lab study. Your doctor might recommend an at-home test first to see if they can rule out sleep apnea in a more cost-effective way.
Multiple Sleep Latency Test (MSLT)
This test will measure how long it takes to fall asleep, known as sleep latency, during the daytime to screen for narcolepsy or idiopathic hypersomnia, which cause excessive daytime sleepiness and napping even after a full night of good sleep.
During this test, you will try to fall asleep several times during the day. If you fall asleep in an average of 8 minutes and reach REM sleep in one nap, you may be diagnosed with idiopathic hypersomnia. If you reach REM sleep in two of your naps, the test is considered positive for narcolepsy.
Purpose of a sleep study
The purpose of a sleep study is to test for issues that can impact your health or prevent you from achieving sufficient quality sleep. The two biggest disorders sleep studies can help your doctor diagnose are sleep apnea and narcolepsy. However, they can also help with the diagnosis of issues like nocturnal reflux, periodic limb movement disorder, or nocturnal seizures.
What to expect during the sleep study process
For a sleep test at a dedicated sleep assessment center, your appointment will be scheduled to begin a few hours before you usually go to bed.
The technicians will attach sensors and wires to your head and body. Some will be glued to you, while others will be wrapped around or clipped to you. These will be set up to interfere with your sleep as little as possible, and they should cause little to no discomfort. (Winter says those with longer hair may have a bit of trouble removing the sensor's adhesive from their hair, but that is typically the only reported discomfort.)
These sensors will measure:
- How long you are asleep, plus how frequently you wake up.
- How long you spend in each stage of the sleep cycle.
- How much oxygen is in your body.
- How frequently your limbs move while you’re asleep.
You can take breaks during the study to go to the bathroom. Most sleep centers have bathrooms adjacent to the sleeping space, though participants typically need to alert the technicians in order to disconnect sensors and move freely.
Many people are concerned they won’t sleep well during the study, but according to Winter, this won’t ruin the results.
“We anticipate that this is not going to be your best night of sleep,” he says. During your first in-lab sleep study, you’ll often experience what’s known as the first-night effect. This is when you sleep less than you normally would due to anticipation, nerves, or just the experience of being in an unfamiliar environment.
Equipment used in sleep studies
The equipment that will touch your body may include sensors glued to your head and body that are attached to wires. These wires are usually long enough to allow you to move around in bed. There may also be sensors lightly clipped around your fingers as well as elastic belts that go around your body.
If you are getting a CPAP titration, you will be fitted for a breathing mask that you will wear while you sleep.
Risk of sleep studies
There are few risks to doing sleep studies.
Physically, some people may experience a minor skin reaction to the adhesive used on the sensors or discomfort removing the scalp sensors from their hair. Many people experience anxiety or nervousness before their sleep study but are still able to eventually relax enough to fall asleep.
“It might take you a little longer to fall asleep,” says Winter, “but we tell people that’s okay.”
All in all, those drawbacks are outweighed by the benefits of the insights you’ll gain into how you sleep and what your true sleep issues might be.
How to prepare for your sleep study
It’s best to avoid naps or stimulant medications like Ritalin the day of the exam. If you’re concerned you won’t fall asleep, Winter says, it’s okay to stay up later than usual the night before or awaken earlier the morning of the study. You can also go to the gym or do other things to get out your physical energy, so you’re more tired before the study.
“We try to have individuals keep a lot of the things that they do at home constant,” says Winter.
Make sure you pack things you normally use at home to sleep, like your white noise machine, favorite pillow, or sleep mask.
“You can bring and wear whatever you want,” says Winter. However, it is important that you’re wearing something. “So if you’re the kind of person that likes to sleep in the nude, that’s perfectly fine; we just prefer you not do that when you’re at the sleep lab.”
Minors must have someone accompany them during the entire sleep study, and if sleeping next to your partner is an important part of getting a good night’s sleep, the lab can often accommodate you.
What do the results of a sleep study mean?
After an in-lab sleep study, your doctor will look at your:
- Oxygen levels, as drops in oxygen while you’re sleeping could be caused by sleep apnea
- Brain waves to assess how long your REM cycles are
- Limb movements, which can be caused by seizures or other disorders
If your doctor diagnoses you with sleep apnea from the results of the sleep test, you may have to come to a second appointment or in-lab sleep study to get a fitting for your CPAP machine.
If you complete an at-home sleep apnea test, and the results rule out sleep apnea, your doctor may order an in-lab sleep study.
How much does a sleep study cost?
If your doctor recommends a sleep study, it is usually covered by insurance. However, your insurance company may require you to take an at-home test before it will cover an in-lab test.
At-home sleep tests can range between $300 and $500 before insurance. An in-lab test can cost as much as $7,000 before insurance. However, costs vary between sleep centers and based on where you live. This site can help you get an estimate of how much your sleep study could cost before insurance.
