Night sleep study: uses, procedure, results


Sleep tests, better known as polysomnograms, are used to diagnose sleep disorders such as sleep apnea , insomnia , and restless legs syndrome (RLS). This includes an overnight stay in a sleep lab that is part of a hospital or outpatient sleep clinic. When you sleep, electrodes attached to your head and body control brain waves, breathing, and movement. A technician watches you sleep through a hidden camera.

Since it can be strange to sleep somewhere other than your bed and know that you are being watched and watched, you may feel some anxiety about this experience. The more you understand why the test is important and what to expect, the more comfortable you will feel.

Illustration by Emily Roberts, Get Drug Information

The purpose of the test

Your healthcare provider may ask you to take a sleep test if you have trouble falling asleep, waking up frequently, snoring, or other symptoms of sleep disorders. A polysomnogram based on a narcolepsy (excessive daytime sleepiness) screening test known as the Epworth Sleepiness Scale may also be recommended.

Sleep studies are designed to diagnose sleep disorders , including:

  • Sleep apnea (complete shortness of breath lasting more than 10 seconds)
  • Periodic limb movements
  • Increased daytime sleepiness
  • Insomnia
  • Circadian rhythm disorders
  • Parasomnias (sleep behavior)
  • Narcolepsy

Since self-reports do not provide a reliable picture of sleep, testing is necessary to get a more complete picture of the quality of your rest and what might be happening in your body to influence it. Electrodes (small metal discs with wires attached to them) placed on your body monitor brain wave activity and sleep stages, heart rate, muscle tone, leg movements, breathing patterns, and sleep. oxygen levels in the blood. The data collected during a full night's sleep is then interpreted.

Before the test

Sleep research requires some preparation, so it is good to know what is recommended before the day of the test.


Most sleep studies are done overnight. According to the National Sleep Foundation , the typical check-in time for a polysomnogram is between 8:00 p.m. and 10:00 p.m., and the usual wake-up times are between 6:00 a.m. and 8:00 a.m. sleep for at least seven hours. If you work nights, some institutions can accommodate classes that take place during the day.


This test is usually done in a sleep center or sleep lab. This can be a special department within a hospital or clinic, or a separate institution. Sometimes even hotels investigate the dream. Sleep laboratories may be accredited centers , which means they meet the standards of the American Academy of Sleep Medicine (AASM).

If your doctor orders you to have a sleep study, he or she will direct you to a laboratory that he knows and trusts. If you are seeking help on your own, be sure to search for properties in your area to find one that is reputable or has received positive reviews.

Usually there are several bedrooms in the sleep center that are dedicated to learning about nighttime sleep. These rooms are designed to be as comfortable and inviting as possible, often with basic bedroom furniture (that is, not like a hospital bed), television, private bathroom, and other amenities.

Typically, a sleep clinic has one or more healthcare providers trained in sleep medicine. Many also practice related disciplines such as neurology, psychiatry, and pulmonary medicine. Other medical professionals who often work at sleep centers include paramedics, nurses, respiratory therapists, and paramedics.

In addition to polysomnograms, most sleep centers also offer other diagnostic tests for sleep disorders and provide treatment.

How to prepare

On the day of your exam, you should follow your normal diet and daily routine as much as possible. But while you won't be testing your sleep until the evening, there are a few things to keep in mind during the test day:

  • Avoid caffeine in any form (coffee, tea, soda, chocolate) after lunch on the day of the test.
  • Enjoy an evening cocktail or a glass of wine. Alcohol in any amount can interfere with sleep (even if you don't realize it).
  • Rinse off hair gel or other styling products. They can interfere with the recording of sleep.
  • Don't sleep during the day.
  • If you take medications regularly, make sure your healthcare provider knows what you are taking. You may need to temporarily stop taking it.

Cost and health insurance

Sleep testing centers can be affiliated with universities or operate commercially, and testing costs vary widely.

Nightly polysomnograms can cost between $ 600 and $ 5,000 (or more) each night; the average size is usually between $ 1,000 and $ 2,000 per night. Insurance, including Medicare, can cover most of these costs. Your final costs will likely depend on your type of insurance, as well as the details of your annual deductible and other factors specified in your policy.

According to the American Sleep Association (ASA), the criteria you must meet for sleep research to be covered also differ. Most companies require that you get tested by a healthcare provider and have certain symptoms before the test. The organization cites the following symptoms as classic examples: excessive daytime sleepiness (EDS), snoring , sleep apnea, night breathing or choking, or a change in certain behavior.

Unfortunately, there are some policies that barely cover testing.
If you are uninsured and plan to pay for sleep research out of pocket, the center may charge you less than the insurance company generally charges.

If you are concerned about the cost of evaluating your sleep, it is best to call ahead and obtain information from a testing center or your insurance company before the study begins. (Your healthcare provider may reveal specific billing codes .) Any reputable sleep center, especially those associated with healthcare facilities, should be able to provide you with a cost estimate prior to your estimate. This is the best way to avoid costly surprises.

Alternatively, if you are having a sleep apnea test, ask your doctor about a home sleep apnea test . This option, which involves borrowing equipment from a vendor, setting it up, and using it yourself, is much cheaper. In general, these tests can cost between $ 150 and $ 500 a night and are often covered by most insurance companies, according to the ASA.

Home test devices do not record sleep stages, ECG heart rate, or leg movements. They focus on measuring breathing patterns, air flow, and oxygen levels. They also record your heart rate and sleeping position. Home sleep apnea tests are best for detecting moderate to severe cases. If the test fails, a central test may be required.

What Brig

It is important to check with your sleep center to see if they have any special restrictions for you. In general, you should bring with you the same things that you usually bring overnight at the hotel.

  • Medications that you take at night or in the morning and that your healthcare provider instructs you to continue during the test.
  • Toiletries
  • Comfortable pajamas and slippers or non-slip socks (if you don't wear clothes regularly, you'll need to do this to explore sleep)
  • Favorite pillows or blankets
  • "Comfort Items" Needed for Sleeping
  • Snack before bed (there may be a small refrigerator in your room)
  • Phone charger
  • A book or other reading material if it is part of your nightly routine.
  • Something for breakfast; the establishment can provide coffee or juice, but not food

If you have a spouse or partner, they will not be allowed to stay with you overnight. Parents of children who undergo a polysomnogram can spend the night in the sleep study room on a rollaway bed. A similar arrangement can be made for a patient with a condition such as dementia or a disability that makes it unsafe to be alone. Please note that the room will be guarded throughout the night.

You will not be able to bring a pet with you, except possibly a service animal. You will need to clear the animal's room in advance and provide all necessary documentation.

During the exam

You will sleep most of the time while you are testing, but it is important to know what will happen so that you can help make the results as accurate and helpful as possible.

Preliminary test

When you arrive for a sleep test, the process is similar to making an appointment with any healthcare provider. You may need to fill out paperwork, including a consent form, and you may need to show your health insurance card and / or copay if you have one.

Once checked in, a sleep specialist will guide you to your room for the night. They will show you the bathroom and a place to put your things, then they will leave you to settle in, change into your nightwear, and go through your normal nightly routine of brushing your teeth, washing your face, etc.

The technician will then spend 45 to 60 minutes preparing you for the sleep study. This time may vary depending on its effectiveness and the complexity of its customization. For example, some seizure studies can take 90 minutes to two hours to prepare.

One of the tests performed during sleep is an electroencephalogram (EEG) , which measures the electrical activity of the brain. To prepare, the technician will measure the dimensions of your head and then use a pencil to mark the locations on the scalp and face where the electrodes will be placed. (The marks will be washed with soap and water). They will then use a cotton swab to apply a lightly abrasive paste to each spot to remove the oil from the skin and make the electrodes fit properly.

The technician will apply a drop of a special paste, reminiscent of cooking oil, on each disc and gently apply it to the marked areas of the face and scalp. The paste keeps the electrodes in place and also allows them to better conduct electrical waves from your brain. Some of the wires on your face may be covered with duct tape. If you are sensitive or allergic to medical tapes or adhesives, notify a specialist in advance so that you can use a type that does not affect you.

In addition to the electrodes, some or all of the following may be part of your sleep study regimen:

  • A flat plastic microphone attached to the neck to record snoring.
  • Adhesive chest pads for monitoring heart rate with electrocardiogram (ECG)
  • Elastic fabric straps that go through the chest and abdomen to measure breathing.
  • Adhesive pads or electrodes placed on the lower leg or forearm to monitor muscle movement using electromyography (EMG)
  • Peripheral capillary oxygen saturation monitor (usually attached to a finger) that continuously measures oxygen saturation
  • An electrooculogram (EOG), which uses electrodes near the eye to measure eye movements.

All these cables will be connected to a small portable box that you can easily take with you if you need to get out of bed (for example, to go to the bathroom).

If you are using continuous positive airway pressure (CPAP) at night, you may be wearing a mask.

Finally, just before going to bed, a technician will insert a nasal cannula, a plastic tube that is placed in your nose, which will measure airflow while you sleep. Most sleep clinics also use thermistors, a barbed wire that is inserted into the nostrils and measures changes in temperature.

Once you've set up, the technician will leave you alone. Enjoy your alone time: read, watch TV, listen to music. It is important not to fall asleep until after your usual bedtime or until you feel drowsy enough to fall asleep. Inform your technician when this happens. (They will tell you how to contact them).

The technician will then help you get into bed and connect the cable box to the computer so they can observe you from another room. The bedroom will likely have a small infrared camera and a two-way speaker. If you need to get up at night, you will seek help for this.

The technician should check the equipment immediately before going to bed. As part of this test, you will open and close your eyes, move your eyes, snore, inhale and exhale, and even move your arms and legs. If something goes wrong with the cable, or if one of them breaks overnight, your technician will come to fix it.


People who undergo sleep research are often concerned about not being able to fall asleep. Surprisingly, most people can sleep even with all the cords, weird furniture, and lots of things that can get in the way. It is extremely rare that someone cannot fall asleep at all.

If this really bothers you, your healthcare provider may ask you to take a medicine that won't interfere with the various tests. The most common sleeping pill is ambien (zolpidem). Do not take this or any other medicine without your healthcare provider's permission.

In the worst case, the tests can be repeated as needed to ensure adequate sleep monitoring and reliable results.

Throughout the test

While you sleep, the electrodes and other equipment will monitor your brain waves, movements, sleep stages, breathing patterns, etc. The technician will monitor you closely from another room. If you wake up at night and need to go to the bathroom or can't get back to sleep, you can seek help from a technician. Otherwise, you will not know what is happening while you sleep.

If sleep apnea is observed, continuous positive airway pressure (CPAP) treatment (if not already established) can be started to find the right pressure to improve your breathing.

Post test

The technician will wake you up at your normal wake-up time. Your electrodes and other devices will be removed quickly, in about 10 minutes. You may need to complete a questionnaire about your night's sleep.

If your room has a shower and you're headed straight to work or an appointment, you can prepare there. You can also eat, drink, and take any of your usual medications.

interpretation of results

Most likely, you will not receive any information about your study until your sleep doctor has read the results. This will probably take a while. Sleep research reports can be five pages long and contain hundreds of data on everything from the stages of sleep you went through to your breathing, heart rate, oxygen levels, muscle movements, snoring episodes, and more.

The ASA lists the following specific aspects of sleep assessment that are seen in most polysomnograms:

  • Sleep efficiency: These results quantify the total number of minutes a person sleeps during a sleep study divided by the total amount of time they slept. The higher the sleep efficiency, the higher the percentage of sleep time compared to waking time. Some reports also summarize the amount of time a person is awake, as well as the length of REM sleep and stages 1, 2, 3, and 4 of sleep.
  • Apnea and Hypopnea Index (AHI): Shows how often a person experiences sleep apnea and hypopnea (partial obstruction). More than five episodes of any of these are considered abnormal AHIs in adults and generally lead to a diagnosis of sleep apnea.
  • Oxygen Desaturation Index (ODI): is the number of times a person's oxygen levels drop during sleep; useful information if someone is being examined for breathing problems during sleep. Oxygen levels above 90% are considered normal.
  • Heart rate: In general, a normal heart rate is between 60 and 100 beats per minute (beats per minute). If it exceeds this number, it is called tachycardia . Less than 60 beats per minute is considered bradycardia .

You will make an appointment with your doctor to review these and other findings from your study and discuss possible treatments if you discover that you have a sleep disorder.

Follow up

For those with excessive daytime sleepiness, multiple sleep delay tests (MSLT) may be performed after a diagnostic polysomnogram. This test consists of taking a nap at two hour intervals the day after the test at night. This is somewhat simplified compared to a baseline survey with fewer dimensions. MSLT can identify narcolepsy, hypersomnia, or the presence of normal daytime sleepiness.

A wakefulness test may also be done as a follow-up. It is typically intended for people who work in professions that require constant vigilance for public safety, such as truck drivers, airline pilots, train drivers, or other transportation professionals. This test ensures that in a quiet and somewhat dark room, the subject can be awake, leaning back slightly on their feet. Falling asleep briefly (or falling asleep) can be a problem if caught.

Repeated sleep studies

Sometimes a sleep study needs to be done again. Your healthcare provider may suggest retesting for a number of reasons.

Changes in your health

If you had a sleep study done several years ago, there may be significant changes in your health that will require a reevaluation of your sleep. A relatively moderate weight change (a 10% increase or decrease in your body weight) may warrant a second study. Weight gain often makes sleep apnea worse, and weight loss can improve or even completely alleviate the condition.

Symptoms that you developed and did not have at the time of your initial diagnosis may also require a sleep reevaluation. For example, if you first develop restless leg syndrome or have frequent leg movements at night, this may require an evaluation. Also, abnormal sleep behaviors, such as REM sleep disorder, can develop later in life and should be assessed through a formal sleep study.

Finally, even more significant changes in health status may require a new examination. Heart failure, stroke, or narcotic injections may be the reasons why there were no changes in breathing during sleep. Each of these conditions can be associated with central sleep apnea , a disorder that often requires two-pronged therapy .

Evaluation of the success of alternative treatments

Many people choose alternative treatments for sleep apnea, including using a dentist for the mouth or surgery . A second sleep study can be a useful way to check the performance of your device and whether the operation was successful.

The oral device can be used while doing a standard sleep study to assess your breathing. The study can also be done postoperatively, usually two months or more after surgery. It is important to compare apples to apples and oranges to oranges: conduct a study of the same type (and in the same location) as the previous test to ensure that other variables do not interfere with the comparisons. If sleep apnea persists despite these treatments, other treatment options often need to be considered.

Unresolved symptoms and optimization of CPAP therapy

Sometimes sleep investigation is repeated to correct unresolved symptoms. If you are still too sleepy , this may be a reason to dig deeper. These replicated studies also allow optimization of treatment, including titration of CPAP therapy.

Persistent and excessive daytime sleepiness may require reassessment as other conditions may occur. The Epworth Sleepiness Scale can be used again to measure sleepiness. A more thorough evaluation is often necessary to clarify the underlying cause of the condition. This may be due to poor sleep, untreated sleep apnea, narcolepsy, or other factors. A diagnostic polysomnogram followed by multiple sleep delay tests (MSLT) can provide evidence of the cause.

The most common indication for a second sleep study is to initiate and optimize positive airway pressure therapy to treat sleep apnea. Sometimes the most effective pressure setting cannot be found, either in an initial study or in home trial therapy. Instead, a second titration study can be used to ensure proper mask fit, improve adaptation to therapy, and determine the pressure needed to maintain the airway during sleep. In some cases, alternative treatments can be explored, including CPAP, bi-levels, and even automatic or adaptive servoventilation (ASV). A sleep therapist can work with you to optimize the therapeutic experience.

Get the word of drug information

As a diagnostic test, the sleep test is definitely one of the most time-consuming evaluations. It can also be one of the strangest, requiring you to put on all kinds of electrodes, cables, and other devices to observe and observe while you sleep. However, sleep centers do their best to make patients feel at home. This should be your experience too, but you need to prepare well for the test. This is the best way to get the results you need to diagnose sleep disturbance (if you have one) and get you on track to finally getting a good night's rest.

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