Generally, a sleep study is a term to describe any test for diagnosing and/or treating sleep problems. These include the portable or home sleep test (HST), the nocturnal polysomnogram (NPSG), the split night study, the PAP titration, and daytime studies that include the Maintenance of Sleep Latency Test (MSLT) and the Maintenance of Wakefulness Test (MWT).

What is a home sleep test?
A home sleep test (HST) is typically prescribed when your doctor suspects you might have a sleep breathing disorder. You will be sent home to sleep that night with various sensors, including some belts, a finger probe, and sensors for your lip and throat. These are designed to record information about your breathing effort, airflow, snoring, heart rate, and oxygen levels throughout the night. From that test, your doctor can refer you to a sleep center if your data suggests you have problems getting adequate oxygen while you sleep.

What is a nocturnal polysomnogram?
A nocturnal polysomnogram (or NPSG) is a diagnostic test conducted in a sleep laboratory which measures physiological data occurring in patients while they sleep. The data come from various kinds of sensors attached to different parts of the body: the scalp, the chin, the brow and cheek, the throat, the nose and mouth, the legs, the chest, and the abdomen.

Sensors on the scalp measure changes in brain wave (EEG) architecture, which show changes in sleep stages. These can also capture unusual brainwave activity that might be related to seizure disorders or epilepsy. Chin sensors (EMG) indicate when patients are awake, tense, or in deep REM sleep. Brow and cheek sensors record different kinds of eye movements (EOG) during both sleep and wake stages. The throat sensor records snoring activity. The nose and mouth sensors measure incoming and outgoing airflow. Leg sensors (EMG) indicate muscle activity in the limbs that can be caused by arousals, movement disorders, and other physiological disturbances. Finally, electrode patches on the chest record ECG patterns (heart rhythms), and belts around the chest and waist show evidence of respiratory effort (or lack thereof), which helps to identify breathing disorders of sleep. An additional device, the pulse oximeter, is clipped to the patient's fingertip; this device measures the amount of oxygen saturating the blood, which lets the interpreting physician know just how much (or how little) oxygen a patient is circulating while they sleep.

Once the patient is hooked up to these sensors, they are asked to sleep in a technologically equipped bedroom and monitored via video and audio equipment for the night. The laboratory technologist collects data which, when scored and interpreted by a sleep physician, can provide answers to explain certain kinds of health concerns, such as excessive daytime sleepiness, morning headaches, low blood oxygen at night, or high blood pressure.

Generally these tests are administered during the evening. However, some patients who work overnight shifts may be scheduled for attended polysomnograms during the day, when they are more likely to sleep.

What is a split night study?
This test is performed for some patients for whom a diagnosis of Obstructive Sleep Apnea (OSA) or upper airway resistance is highly likely. This is often determined by a pulmonologist who specializes in heart and lung disorders. A split night study starts out like the NPSG; the patient is prepared in the same way and the same signals are attended during the test. However, respiratory events are a chief focus of observation in this test. Respiratory events are moments during sleep when the airway is partially or completely obstructed for at least ten seconds, or when arousals occur due to airway resistance, such as in the case of heavy snoring. Respiratory events in a split night study are tallied over the first third of the test and, if the patient has experienced enough to meet lab protocol, they are given positive airway pressure (PAP) therapy to help eliminate these events.

What is a a PAP titration?
This study involves the use of a positive airway pressure device and mask to identify the best therapeutic measurement of air pressure for people with OSA. Positive airway pressure is essentially delivery of very light puffs of air to the patient's upper airway in order to assist the patient in completing inhalation and exhalation, both which may be obstructed due to confirmed issues of blockage in the upper airway.The patient is acclimated to the mask by wearing it before the study using very light pressure. Then they are hooked up like they would be in an NPSG. However, in the case of a PAP titration, they start their study using PAP therapy. As they sleep, the technologist remotely and digitally adjusts the therapeutic level of positive pressure feeding through the device and mask, as well as humidity and pressure support for exhalation, until they determine the pressure which most benefits the patient is the most comfortable for them.

What kinds of PAP titration are there? 
There are different kinds of PAP therapies available, each designed to address different kinds of sleep disordered breathing, which include obstructive sleep apnea (OSA), central sleep apnea (CSA), Cheyne-Stokes breathing (CSB), Sleep Related Hypoventilation/Hypoxemic Syndrome, and other conditions. The kind of PAP therapy a patient is given relates specifically to the kind of diagnosis they have.
  • CPAP stands for Continuous Positive Airway Pressure; CPAP therapy offers delivery of a single air pressure for both inhalation and exhalation. This is most often used to treat OSA.
  • BiPAP is shorthand for Bilevel Positive Airway Pressure, in which the pressure for inhale varies from the pressure for exhale. BiPAP is often used to treat more severe cases of OSA and CSA.
  • AutoPAP is a device which delivers pressure based on the device's ability to use algorithms to detect a patient's breathing and saturation needs. AutoPAP (or APAP) is used to treat OSA.
  • Adaptive servo ventilation, or ASV, is a kind of "smart" PAP delivery device which continuously adjusts to the patient's respiratory needs. It is used to treat more complicated CSA and central origin sleep disorders like complex sleep apnea.
  • AVAPS, or Average Volume Assured Pressure Support, is a unique treatment used for patients who not only need PAP delivery but ventilation in order to breathe through the night. AVAPS helps patients who are already using oxygen supplementation at night.
What is the Maintenance of Sleep Latency Test (MSLT)?
This test is usually performed on the morning following an NPSG. Patients who are excessively sleepy during the day undergo several daytime nap periods to record their brain wave patterns at those times. Some of the overnight sensors are removed while others are left on for up to 5 tests performed about 2 hours apart. This test helps to identify conditions like Idiopathic Hypersomnia, Narcolepsy with or without Cataplexy, and Klein-Levin Syndrome ("Sleeping Beauty" disorder).

What is the Maintenance of Wakefulness Test (MWT). 
This test is performed during the day by having patients, who have been set up with a specific set of sensors, sit in a dark room for a certain period of time to determine how well they can stay awake in low stimulus conditions. This test is often used for commercial truck drivers, airline pilots, bus drivers, and other operators of public or commercial vehicles or industrial equipment who may be at risk for falling asleep at the wheel or while operating machinery. 

Will insurance cover my sleep study?
Generally, sleep studies are considered medically necessary because they are critical to identifying underlying sleep disorders, especially those related to disordered breathing. Sleep disordered breathing has been shown to contribute to hypertension and obesity and to exacerbate other chronic illnesses, such as diabetes, heart disease, and COPD. Sleep disordered breathing is also a  major public safety concern for patients who are employed to operate vehicles or machinery in public or workplace environments. Read more about Drowsy Driving here.

Different insurance companies cover different kinds of tests and durable medical equipment (DME) related to sleep testing, so it's best to consult your insurance company to see what they will reimburse. You will likely need to be referred for a test and might need to have your studies and equipment pre-approved by your insurance company before taking a test. Often a doctor's choices for treatment will be limited by what your insurance is willing to reimburse. It is advised that all patients look at their insurer's policies regarding failed or incomplete tests. If a patient leaves a study against medical advice, the insurance company may or may not reimburse, leaving the patient responsible for payingpartially or completelyfor his expensive test.

Fortunately, most sleep disorders are treatable and therapies are generally covered by most insurance companies. In particular, treatment for apnea can result in improvements in blood pressure, weight management, blood sugar levels, and even depression, which support insurance payers' demands for positive outcomes following long-term therapies like CPAP.

How do I prepare for a sleep study before I get to the lab?
It's best to do the following before coming in for a test:
  • Shower 
  • Come in with clean, dry hair
  • Remove makeup
  • Eat your evening meal 2 or more hours before coming to the lab
  • Avoid alcoholic or caffeinated beverages or foods 5 or more hours before coming to the lab
  • Prepare to be told you cannot smoke at least 30 minutes before your study starts (which includes vaping)
  • Take your usual medications, but do not take any sleep aids until you've alerted your technologist to the fact you are taking them; it is important to start your study awake!
  • Manage your diabetes medications as usual
  • Expect to start your sleep study with all electronicsincluding the TV, cellphone, and radioturned off, even if it's normal for you to have these on at bedtime
What things should I bring to the lab for my sleep study?
  • Clothes to sleep in (do not bring lingerie); pajamas, nightshirts, t-shirts, and shorts are all acceptable. Nude sleeping is not permitted in the sleep lab
  • Slippers to walk in, and a robe; some labs will set up patients in their rooms, while others will set them up in separate locations inside the lab
  • Comfort items like a favorite pillow, blanket, or stuffed animal
  • Your evening medications (note: technologists are not permitted to administer medications). These could include your usual prescriptions as well as over-the-counter pain relievers, decongestants, nose sprays, antacids, heartburn medications, and the like
  • A white noise machine, if this is helpful for you (some labs have these available)
  • Your usual personal care items like shampoo, conditioner, soap, toothpaste, toothbrush, deodorant, etc. Though many sleep labs are set up to resemble hotel rooms, they are still medical facilities and do not always provide these personal care items
  • If you are diabetic, having some snacks on hand is okay if that will help you regulate your blood sugar through the night.
  • Most labs have overhead or standing fans to help keep rooms cool for patients who need them
What things should I NOT bring to the lab for my sleep study?
  • Anything with a strong fragrance; most labs are fragrance-free environments
  • Pets
  • Loved ones may come with you to the lab to help you get comfortable, but they cannot typically stay the night unless they are pre-approved as caregivers
  • Fast food or other carryout food items that have a strong aroma
  • Electronics like laptops, cell phones, and handheld gaming devices; if you do bring them with you, please be prepared to turn them off completely for the night
  • Alarm clocks; you will be woken by the technologist in the morning upon completion of the study
How will the technologist prepare me for a sleep study once I'm at the lab?
Depending upon the nature of your visit, the technologist will prepare you for your study in various ways. Typically, preparation will include application of scalp and body sensors and trying out several kinds of PAP masks to find the one that fits you best and is most comfortable for you, in the event you will need it. The technologist is also a sleep educator who is trained to answer all your questions about the test, so feel free to ask questions of them or express any fears or concerns you may have.

Right before the study begins, they will work with you to perform calibrations. These include little exercises you complete at their instruction, such as blinking your eyes or pointing your toes, so they can capture a digital record of the baseline measurements related to each of the sensors you have attached to your scalp and body. Each patient displays different variations on these signals (size, shape, speed), so these calibrations come in very handy for the scoring technologist and physician later when they prepare to score and interpret your study after you've gone home.

The technologist cannot discuss your test results the following morning, as a typical test includes about 800 pages of raw data that still require scoring before the physician can interpret the results. However, your technologist can take notes addressing your concerns which can be forwarded on to your physician with your study. Technologists are not physicians and are, therefore, not qualified to diagnose patients.

What medications can I take before my sleep study?
Unless advised differently by your physician, take your normal medications; if you have sleep aids, hold off taking them until you have had a discussion with your technologist, as they will direct you to the proper time to take them. If you have problems with heartburn or pain or congestion, you will be allowed to take medications for these as necessary to help you get to sleep comfortably. However, the lab will not necessarily have these on hand, so please make sure and bring your favorites in case you need them.

What happens if I have trouble sleeping during my sleep study? Won't it ruin my test?
Most patients are expected to be a little on edge at first; this is normal. A sleep study captures a whole range of issues that can explain problems with insomnia or sleep maintenance, as well as those issues that occur while you are asleep. Your best approach is to try to sleep as well as you can and try not to worry about your sleep quality; the technologist runs the study in such a way as to account for so-called "first night effect" (which impacts nervous patients who can't sleep initially) and very rarely does anxiety at the beginning of the night impact the overall efficacy of the test.

Will I have to have more than one sleep study?
It depends upon what your particular sleep issues are. Some sleep disorders are adequately diagnosed after a single study, while other sleep disorders require different tests on different nights and sometimes even during the day to get at the root cause of the problems. There is no typical procedure; each test for each patient is determined by their unique needs.

For example, the split night study is set up with a default diagnostic-to-therapy course to allow technologists to administer PAP therapy to those patients who have more severe breathing issues during sleep. This process helps to prevent having patients come in for yet another test when the evidence overwhelmingly supports their need for respiratory therapy. However, it's important to note that a patient who has a split night study who does not meet the criteria for using PAP therapy that first night might still need to come in for a titration on another night.

What are the technologists doing while I'm asleep?

  • They monitor the data collected by the signals attached to your scalp and body
  • They write regular reports and tag specific data inside the study as it happens so the scoring technologist and physician can interpret the study later
  • They adjust PAP pressures and settings 
  • They fix any sensors that might have fallen off or might otherwise not be working properly in order to collect the clearest data
  • They assist you with getting to the bathroom in the middle of the night
  • They help you with comfort issues (more pillows, cooling fans)
  • They update medical records related to your study
  • They prepare your followup paperwork

What time will I have to get up? 
Generally speaking, patients are woken up by the technologist between 5 and 6am. Following "Lights On," they will calibrate your signals, unhook you from all the sensors, go over your followup paperwork with you, and offer any assistance you need in getting ready in the morning. This usually takes less than 30 minutes, after which you are free to clean up. Some labs offer breakfast foods; hospital-based labs often hand out coupons for free breakfast in the cafeteria.

The technologist you have worked with at the beginning of your study will be the same technologist who will unhook you. They also will be cleaning up and sterilizing all the equipment; in some labs, they are also tasked with changing linens and towels out and stocking the bedrooms and bathrooms. Sleep lab techs generally work 12-13 hours overnight, then go home, sleep during the day, and return to work the next night.

How soon will I find out my sleep study results?
Most labs will get back to you within 2 weeks. Your sleep technologist should give you information about the process following your study before you leave the lab.

Why do the technologists have to audio and video record my study?
Often the sensors attached to the patient show unusual signals. Using video and audio feeds live helps the technologist to determine whether the unusual signals are due to sensor malfunction rather than symptoms caused by sleep disorders or harmless patient movements.

Body position, an important part of data collection, can be confirmed via video feed when a signal isn't working right. Snoring is also confirmed through audio feed. Some kinds of sleep disorders, those involving unusual movement or vocalization, require audio-visual records to confirm.

Generally, the image of the patient, which is black and white, is kept in a small window on the computer monitor in the lab. The technologist is more likely examining the patterns coming from the signals more closely than they are the patient's sleeping form. Physicians who have questions about certain aspects of the study may call up both the audio and video recordings to see what happened in those moments during the study.

Finally, because of the somewhat intimate nature of the sleep test, an audio-video recording offers both the patient and the technologist legal protection against any misunderstandings which might occur while the technologist is in the room with the patient at night.