What Is a Sleep Study?

A Complete Guide to Polysomnography Testing in 2022

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Illustration of sleep study in lab

Everything you need to know about a sleep study (polysomnography), the different types, what they can diagnose, and what to expect if you think you may have a sleep disorder.

Sleep is critical for good health and a positive mood. However, sleep is also something many people report issues about within their day-to-day lives. 

For those with sleep issues, a sleep study is the best way to determine where the issue is. Given the number of adults that report issues staying asleep or feeling rested, it’s in your best interest to learn what you can about your sleep health to empower you to live a better, more active, and more present life. 

There are a few things you’ll probably want to know to be prepared, such as how long sleep studies take, what they measure, and how you might be able to set yourself up for the most accurate results in the days leading up to the test. 

We’ll cover that and more, so keep reading to find out everything you need to know about participating in a sleep study.

What Is a Sleep Study?

A sleep study is an overnight exam where sleep specialists review what goes on with your brain and body during sleep. These examinations are non-invasive and involve hooking you up to a collection of instruments that measure your muscle impulses, brain activity, blood-oxygen saturation, heart rate, breathing, and eye movements. 

Sleep studies can occur in either a sleep lab or at home using borrowed equipment. A sleep lab refers to a location where technologists connect the instruments to the patient before they sleep overnight. At-home sleep tests tend to involve compact versions of the instruments that aren’t as comprehensive but allow those that can’t leave home to get results.

Types of Sleep Studies

There are several types of sleep studies a person could undergo, including an at-home study and an in-lab sleep study. The most common forms of sleep studies include: 


Polsomnographies are the baseline test performed during a sleep study. These tests measure vital signs and bodily responses to sleep, including blood oxygen levels, muscle twitches, eye movement, and other sleep quality indicators. 

Many known sleep disorders will first be detected through polysomnography. The results generated by this suite of recordings will allow your sleep technologist or healthcare provider to determine what further sleep studies you should undergo, as well as provide data that could lead to a diagnosis. 

CPAP Titration

Continuous positive airway pressure (CPAP) is the gold standard of treatment for those suffering from sleep apnea. CPAP titration involves a sleep lab technologist measuring the amount of air pressure required from a CPAP machine to most significantly reduce the number of apneas you experience in a night. 

These tests can sometimes require multiple overnight visits to a sleep lab for proper determinations. By having you run this test multiple times, a sleep doctor can verify if the CPAP pressure alleviates the issues caused by sleep apnea. 

Sleep doctors tend to pair CPAP titration with polysomnography during a split-night sleep study. During a split-night sleep study, you’ll have polysomnography performed during the first half of your sleep study and the CPAP titration done during the second half. This split between two tests rarely comes up past the first sleep study. 

Multiple Sleep Latency Test

This test measures the length of time it takes for you to fall asleep and how your sleep changes between phases during the night. It also measures how fast you enter REM sleep during a daytime nap. 

In general, these tests work in finding sleep disorders related to daytime sleepiness, such as idiopathic hypersomnia or narcolepsy. Given what is known about REM sleep and restfulness, finding issues relating to entering deep sleep stages during rest can account for symptoms related to these illnesses. 

What To Expect at a Sleep Study

How does a sleep study work? It can seem daunting or strange for those who have never done a sleep study. So, to help ease any concerns, here is what happens during a sleep study, so you know what to expect. 

Before the Study

Here are some helpful tips to keep in mind to make the most out of the time before your study:

Where Can I Get a Sleep Study Done?

Most sleep studies will require you to stay overnight at a sleep lab or undergo a sleep study in hospital care. Check-in times for these studies are later at night, and the departure will be sometime the next morning. Some facilities account for folks that work night shifts, but that’s a detail that needs to be confirmed before you book the sleep study. 

In general, sleep centers host the facilities for sleep studies. These facilities specialize in sleep medicine and sleep disorder diagnosis and typically staff doctors and technologists with training, knowledge, and experience specific to sleep medicine. 

Participants in a sleep study will go to an assigned bedroom for monitoring. These bedrooms tend to feature accommodations akin to what you’d see in a hotel room to help you feel more relaxed. The beds might not match what you have at home, but they should be more comfortable than a cot in the hospital. You’ll also be allowed to bring some personal items to help make you a bit more comfortable before bed. 

How To Have a Sleep Study Done: Preparation

During the daytime, before your sleep study, you should follow along with your day as normal. Keeping with your standard schedule will give a more accurate reading than trying to do something you wouldn’t normally do. 

Still, there are some things you should and shouldn’t do before heading over to the sleep medicine facility, such as: 

  • Avoid caffeine during the afternoon to prevent it from interfering with your sleep during the study.
  • Avoid alcohol consumption as it can also interrupt sleep.
  • Wash out any hair products from your hair to prevent interference with the sleep recording.
  • Don’t nap the day you have your sleep study.
  • Take and bring the regular medications you would take in the evening and the next morning. Ensure your healthcare provider knows you’re on the medication before scheduling the sleep study!
  • If possible, stay up late the night before and try to wake up early the day of your study so that falling asleep is easier and quicker for you.

The doctor heading your sleep study will also likely share most of these tips with you well before the study. 

What To Bring With You

When packing up for your stay at the sleep facility, you’ll want to bring these items with you:

  • Medications you would normally take at night or the next morning
  • Toiletries for the next morning
  • Comfortable sleepwear, pillows, and blankets
  • Your phone charger
  • A book or other reading material if you use that to fall asleep
  • Something small to eat in the morning if your facility doesn’t provide breakfast

Usually, spouses and pets cannot stay overnight with you at the sleep study facility. Some accommodations will be made for parents of small children or dementia patient caretakers, but the sleep study personnel handle these instances on a case-by-case basis. If you have difficulty getting away from your schedule for a night in a sleep lab, a home sleep study may be a good option for you.

During the Study

You’ll be asleep for the majority of your stay, but here’s some info about the parts you’ll be awake for: 

Arrival at the Facility

Your arrival at the sleep study location will play out much like checking in for any other healthcare appointment. In addition to filling out paperwork and consent forms, you’ll present your health insurance info and pay for the visit.  

Setting Up For the Study

After your check-in, a sleep technician will take you to the bedroom you’ll use for the study. They’ll give you a rundown of the place and give you a chance to change into your sleepwear for the night. 

While every sleep study uses different equipment, most use an electroencephalogram (EEG) to view brain activity at night. Before hooking up the EEG, the technician will measure your head and apply the pads to your face and scalp. This is also when the technician will set up your CPAP machine if you’re undergoing a titration study.

The Actual Sleep Study

Once you’re hooked up to the necessary instruments, you’ll be free to head to sleep. Despite the nerves many people feel and the equipment, most folks sleep the full duration of their sleep studies. 

If you believe you’ll have issues falling or staying asleep, a doctor might allow the use of a sleep aid during the study. The most common choice is Ambien (zolpidem), but you’ll need approval from your regular doctor before receiving a sleep aid for the study. 

Besides these tidbits, you’ll be asked to sleep for the night. Follow your usual nightly routine and fall asleep as best as you can. 

Miscellaneous Info

While you sleep, the instruments will monitor your brain activity, breathing patterns, muscle twitches, and similar metrics. Each of these data points will help your sleep doctor find out what causes the sleep issues you experience. 

If you wake up in the middle of the night, do your best to fall back asleep. There is a bathroom in each bedroom at most sleep test centers, so feel free to use these during the night. You might need help from the sleep technician to unhook from the instruments, but they’re trained to assist you with this, so don’t be afraid to ask for help! 

Results and Scoring

The next morning, you’ll be awoken by the sleep technician at your wake-up time. They will help remove the instruments as well as any pads needed to hook the instruments up to your body for the sleep study. You might also have to fill out a survey about how you slept to give your doctor some qualitative data about how your sleep felt. 

The sleep study data will most likely not be shared with you until your doctor has a chance to review it. For most folks, this takes about two weeks for the doctor to review the information and contact you about your results and next steps. 

The four data points your doctor will look at the hardest will be: 

  • Sleep efficiency: The total number of minutes you slept divided by the time you were allocated to the room. This value determines how much time you spent asleep during the study and helps indicate any interruptions for your doctor. 
  • Apnea hypopnea index (AHI): This value shows how often you experienced sleep apnea or partial obstruction of the throat during sleep. Doctors generally want this number below five in patients without diagnosed sleep apnea. 
  • Oxygen desaturation index (ODI): This number shows the doctor how often your blood oxygen level dropped while asleep. Patients with normal oxygen levels will have this value at 90% or higher in their chart. 
  • Heart rate: Normal heart rates range between 60 and 100 beats per minute (bpm). Abnormalities here can indicate physiological issues are causing the sleep issues. 

Your doctor should contact you once they have a chance to review your sleep study data. They’ll cover the relevant parts of the study and explain what each value means if needed. The doctor should also cover which numbers do not meet standard ranges and what that means. 

What Happens After a Sleep Study?

Since most folks start with a polysomnogram, the follow-up from a sleep study depends on the results of the polysomnogram and what data points don’t indicate standard sleep activity. 

For those with daytime sleepiness, multiple sleep latency testing might follow from this study. This testing will give your healthcare provider a better understanding of how your body handles naps at the brainwave level. It will give them a better chance to diagnose the problem, such as narcolepsy or hypersomnia. 

Maintenance of wakefulness tests can also be a follow-up procedure to a sleep study. These tests are for those who work jobs that require sustained attention or alertness, such as truck drivers and similar transportation workers. This test proves that the individual can remain awake and alert in quiet, dark spaces such as truck cabins or airplane cockpits. 

Individuals needing CPAP aid will work with their doctors to select the best at-home unit. CPAP titrations, if performed during the sleep study, can assist patients in finding the positive pressure they need to alleviate their sleep apnea during rest. Doctors can also help patients arrange payments for CPAP machines with their insurance.

Finally, there is a chance that your doctor will want a follow-up sleep study if things change in the future, especially if you receive a sleep disorder diagnosis. In case you aren’t sure, these circumstances would indicate that you should repeat the sleep study: 

  • Excessive changes to your health, such as a major loss or gain of weight, heart disease diagnoses, and the new usage of narcotic medications.
  • Making a significant change to the amount of alcohol you consume or cigarettes you smoke. 
  • The acquisition of an oral appliance or surgical treatment to cure apneas.
  • Unresolved sleep apnea or other sleep disorder symptoms. 

Specific circumstances for your condition will be set by the doctor, as well. 

What Can a Sleep Study Diagnose?

There are many reasons for a sleep study. Sleep studies help provide data about a wide range of metrics, especially when polysomnography comes into play. By measuring the various signs of sleep responses, sleep doctors can obtain the information they need to diagnose someone with one of the various sleep disorders we know of. 

Here are some of those sleep disorders and what they generally look like: 


Insomnia refers to a difficulty or inability to fall asleep. This disorder tends to cause issues or impairments during the daytime due to a lack of sleep. 

This disorder comes in two main forms: chronic and short-term. Chronic insomnia refers to a constant difficulty with falling asleep, while short-term insomnia is experienced in short bursts or sporadically. 

While short-term insomnias tend to be caused by life stressors, chronic insomnias can have both lifestyle and physiological origins. Determining the origins of your insomnia can be just as important as finding out how your brain and body react to sleep. 


Narcolepsy is a disruption of the sleep-wake cycle. Most people know this disorder for its most common symptom: excessive daytime sleepiness (EDS). This symptom occurs because the brain doesn’t regulate wakefulness and sleep the way that it should.

In general, this disorder comes from a disruption to the natural cycle of sleep stages. A sleep study can help healthcare providers understand where the brain disrupts during the sleep cycle and determine the best treatment measures for that disruption. 

Periodic Limb Movement Disorder

Periodic limb movement disorder (PLMD) refers to an ailment that causes the lower limbs to twitch or regularly move throughout a night’s sleep. These motions tend to occur every five to ninety seconds and can last for an hour in some cases. These motions disrupt your ability to enter or stay in a deep sleep. 

While this disorder can occur on its own, PLMD can also happen in response to other conditions such as iron deficiencies, excessive caffeine use, anemia, or side effects reactions to certain medications. 

REM Sleep Behavior Disorder

REM sleep behavior disorder refers to a condition of body movements and vocalizations during sleep. Specifically, these sudden motions occur alongside vivid dreams during REM sleep.

Normal REM sleep places the patient into atonia, or temporary muscle paralysis, so that the body doesn’t move in response to the dreams created by REM sleep. Those with this disorder don’t enter atonia, causing them to move wildly during REM sleep and unwittingly act out parts of their dreams. 

Restless Leg Syndrome (RLS)

Willis Ekbom disease, also called restless leg syndrome (RLS), causes uncomfortable sensations in the leg. Itching, prickling, or pulling sensations originate from the legs for those with this disease, causing an urge to constantly move the legs. Movement abets these sensations for a little bit, but their presence during times of rest prevents people with this condition from getting restful sleep. 

While the disorder can impede other parts of life like sedentary work days, the vast majority of RLS patients report a sleep-related issue to their doctors. 

Sleep Apnea

For those that experience abnormal reductions or disruptions to their breathing during sleep, issues relating to their sleep are ascribed to sleep apnea. Sleep apneas can prevent restful sleep from occurring and lead to serious health consequences if left untreated for long periods.

Sleep apnea testing procedures can either eliminate apnea as a diagnosis or present in three forms: obstructive, central, or complex. Obstructive sleep apneas come from blockages in the back of the throat during sleep. This is the most common form of sleep apnea, and can be a result of an excessive amount of tissue in the soft palate that falls down into the airway when the muscles around the throat relax during sleep. Because of this blockage, the person experiencing it typically wakes up briefly to clear the obstruction (typically in a fit of coughing, gasping, or choking) before falling back asleep, and often won’t even realize what’s happening. 

Central sleep apneas come from disrupted communications between the brain and muscles involved in breathing. These irregularities cause shallow or paused breathing during sleep. 

Complex sleep apnea is a combination of obstructive and central apnea, and requires more specialized equipment, typically an advanced BiPAP machine, to effectively treat.

Sleep Talking (Somniloquy)

Sleep talking is referred to as a parasomnia or abnormal behavior during sleep. While most parasomnias occur during the REM stage of sleep, this disorder can happen at any point during the sleep cycle and is distinct from other vocalizations like groaning or REM sleep behavior disorders. 

It’s not currently clear what the cause of sleep talking is. While this behavior may relate to dreams, there hasn’t yet been a proven connection between dream activity or content and sleep talking behaviors. The fact that most sleep-talking behaviors are silent or incomprehensible doesn’t help in this determination, either. 


Sleepwalking is another parasomnia. This behavior tends to occur in non-REM sleep and causes a person to exist between a wakeful and sleepy state. 

In this state, the individual may not limit themselves just to walking. Routine behaviors, such as dressing or running, and complex behavior, such as trying to drive a car, can occur when someone is experiencing a sleepwalking episode. These episodes can last anywhere from a few seconds to a half hour.

In addition to acting as a complication from other sleep disorders, lifestyle choices like alcohol consumption and frequent exposure to stressors can lead to sleepwalking episodes. 

Why Do I Need a Sleep Study?

Sleep studies can help those that suffer from poor sleep at night, but they are not the correct call for everyone. So, who orders a sleep study? Doctors will prescribe a sleep study based on what symptoms you present and how those symptoms affect your health. 

Individuals who experience issues with falling or staying asleep should consult with a doctor about a sleep study. This recommendation includes those that suffer from things like fatigue, drowsiness, or depression. Those who are obese or overweight should also look into sleep studies because of the link between obesity and sleep apnea

Those that go through sleep studies and still have not found the solution to their problem should reach out to their doctors. Doing so might entail a follow-up sleep study to assist you in finding the root of your sleep problems.  

How Much Do Sleep Studies Cost?

Sleep studies range widely in price due to the various ways patients can perform the test and how the sleep study changes based on the presumed sleep issues. Health administration differences, such as clinical billing cycles and the patient’s insurance provider, can also change the price of a sleep study. 

As a trend, in-center sleep studies are more expensive than at-home studies. An in-center sleep study ranges between $400 and $3,000 before insurance coverage. However, at-home studies can cost between $150 and $600 before insurance, meaning these studies are much more affordable and approachable for both you and your insurance provider on average. 

Frequently Asked Questions

Here are the answers to some of the common questions out there about sleep studies and how they operate: 

What Do They Do During a Sleep Study?

During a sleepy study, a sleep technician will use and monitor various instruments to gather data about how your body reacts to sleep. Brain activity, blood oxygen levels, and muscle activity are common data points that the instruments gather during your study. 

How Long Is a Sleep Study?

Most sleep studies last for one night. These studies allow your doctor to obtain data about how you sleep on an average night and what activity abnormalities there may be. 

Multiple tests might be needed depending on your results and the diagnosable conditions. Most repeat studies require another overnight stay or an extended period of you going between naps and wakefulness. 

How Long Do Sleep Study Test Results Take?

Your doctor will most likely need a week or two after the study to review the results and determine your diagnosis. It’s not uncommon for a sleep study to require multiple nights of data in instances where results are inconclusive, or a myriad of disorders is suspected, so some diagnoses may come more quickly than others.

Is a Sleep Study Worth It?

A sleep study can be well worth it if you have chronic issues falling asleep. There are many causes of poor sleep, some of which can only be detected via electronic medical equipment. Poor sleep is detrimental to your health and can even be fatal depending on the underlying cause, so it’s in your best interest to find out why you’re sleeping poorly and seek treatments or solutions for it. A home sleep test is a viable and affordable way to rule out obstructive sleep apnea, which is one of the most common sleep disorders there is.

What Should You Not Do Before a Sleep Study?

You should avoid consuming caffeine and alcohol before a sleep study, as these chemicals affect your sleep cycles. You also should avoid napping the day before the sleep study to ensure you are sleepy enough at the end of the day to sleep at the study facility. 

Is a Sleep Study Painful?

Sleep studies are not painful. None of the equipment requires an incision or needles to measure your sleep. Plus, the wires and cables of the devices are long enough to allow active sleepers to toss and turn during sleep. 

Should I Be Scared of a Sleep Study?

There is nothing to fear about sleep studies. While sleeping in a new place can be strange or off-putting, a sleep study does not require invasive measures or constant surveillance from a technician. You will be left alone to rest for most of the sleep study. 

Can I Watch TV During a Sleep Study?

The bedrooms of most facilities will not have TVs in them. TVs give off light that can affect your body’s ability to fall asleep. Additionally, television can keep the brain active later than it would otherwise be, thus skewing the sleep study results. If, however, watching TV before bed is a normal part of your routine, you may be able to arrange something with the sleep center to make you feel more at home. 

Can I Go to the Bathroom During a Sleep Study?

Most sleep study facilities have bathrooms in the bedrooms for their patients. You are free to use these bathrooms during your stay. Just be aware that, depending on your sleep study, you may need help from a technician to disconnect from your monitoring equipment.  

Can I Be on My Phone During a Sleep Study?

While most facilities let patients use their phones while getting ready for bed, you won’t be able to use your phone once you get into bed. Cell phones give off light that can affect sleep, thus skewing the results of the sleep study. 

What Happens if You Can’t Sleep During a Sleep Study?

If you cannot sleep during a sleep study, the doctor may reschedule the sleep study or prescribe a sleep aid medication to assist you for the night. However, most patients find they can sleep for some or most of their sleep studies. Bringing a melatonin supplement or other natural mild sleep aid may help if you’re concerned about not sleeping through the night. To help you prepare, read our helpful tips on what to do if you can’t sleep during your sleep study.

Can a Sleep Study Detect Heart Problems?

One of the main data points sleep doctors look at is heart rate. Irregularities in heart rate can indicate that sleep problems come from a deeper physiological problem. However, your sleep doctor will refer this information to a cardiologist rather than make a diagnosis themselves. 

What Is the Next Step After a Sleep Study?

After your sleep study, your doctor will work with you to either schedule another study or diagnose you and prescribe medications or treatments. 

Final Thoughts

A sleep study is a medical procedure where you’ll sleep at a sleep testing center to monitor your brain and body responses to sleep. This non-invasive procedure gives sleep doctors the information they need to recommend more advanced monitoring tests or diagnose you with a sleep disorder. 

So, what do sleep studies show? There are many benefits of sleep study data collection. Many sleep disorders can be found with one or a few sleep studies, ranging from sleep talking and sleep apnea to restless leg syndrome and narcolepsy. 

A sleep study does not require a great deal of effort on your part. Once checked in, you’ll change into your sleepwear, connect to the monitoring devices, and sleep overnight at the facility. In the morning, you’ll change into your day clothes and leave the facility while your doctor reviews the data. You can expect to learn about the results of your sleep study within the following two to three weeks.

What Next?

If you or someone you know has issues with sleep, recommend that they have a sleep study performed. Many doctors recommend at-home tests for minor to moderate symptoms, meaning you might not even have to leave home to learn more about your sleep patterns! 

Nate Devore
Nate Devore
For over 15 years Nate has been obsessed with solving his own personal and difficult health challenges related to sleep, energy, and fatigue. As one of our sleep experts at sleeping.com, Nate is passionate about helping you get the best night’s sleep possible.

Medical Disclaimer: The content on this page should not be taken as medical advice or used as a recommendation for any specific treatment. Always consult your doctor before making any decisions.

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