woman at sleep center study

What to Expect at a Sleep Center

Sleep Disorders

woman sleeping sleep center

There are over 100 distinct types of sleep disorders including those that cause difficulty sleeping at night and those that produce excessive daytime sleepiness.
Here is a list and brief explanation of some of the more common disorders:

Sleep-related Breathing Disorders (Sleep Apnea)

Sleep apnea is a common disorder whereby a person’s breathing stops momentarily or he or she takes very shallow breaths during the night. These pauses in breathing last from a few seconds to minutes and may happen 30 or more times an hour.

Sleep apnea is almost always a chronic condition that causes the sufferer to go from a deep sleep into a light sleep. The quality of sleep is poor, creating a tired feeling during the day. Sleep apnea is a leading cause of excessive daytime sleepiness.

Obstructive Sleep Apnea (OSA) occurs when the throat muscles intermittently relax and block the airway. Central sleep apnea (CSA) happens because the brain sends improper signals to the muscles that control breathing.


The breathing sound produced when the air movement is obstructed, causing a vibration of the respiratory structures when you are asleep is called snoring. In many cases, the sound can be almost deafening and obnoxious. Snoring during sleep may be an indication of obstructive sleep apnea (OSA).

Upper Airway Resistance Syndrome (UARS)

Upper airway resistance syndrome is a sleep disorder characterized by airway resistance to breathing. While someone sleeps, the airway muscles relax, which partially closes the airway.

A person with UARS has an existing airway that is small, so when sleeping the airway becomes even smaller. UARS patients experience daytime sleepiness and excessive fatigue.


Insomnia is a disorder causing difficulty falling asleep or staying asleep. People with insomnia usually experience one or more of the following symptoms: low energy, fatigue, mood shifts, difficulty concentrating, and decreased performance in work or at school.

Shift Work & Circadian Rhythm Disorders

Insomnia and constant tiredness are the main symptoms of Shift work sleep disorder (SWSD). The condition most often affects shift personnel who work at night or during what is his or her normal sleep period.

Restless Legs Syndrome

Restless legs syndrome (RLS) occurs during sleep. A neurologically-based disorder, patients experience uncomfortable feelings in his or her legs in addition to uncontrollable urges to move their legs as moving them is the only way to relieve the discomfort.

Pediatric Disorders

Pediatric Sleep Disorders are disturbances often due to temporary or chronic medical problems and are observed in as many as 25 to 30 percent of children. The disorders may range from insufficient sleep, bedwetting problems and sleepwalking to sleep apnea and narcolepsy.

Narcolepsy, Kleine-Levine Syndrome & Other Hypersomnias

Narcolepsy is a neurological disorder that causes excessive daytime sleepiness and intermittent, uncontrollable sleep episodes during the daytime.

Known to most patients as Sleeping Beauty syndrome, KLS or Kleine–Levin syndrome, though rare, causes persistent episodic hypersomnia, mental confusion, and changes in temperament. Patients have increased appetites, engage in hypersexual activity, and can also experience other excessive behaviors.

Nighttime Sleep Behaviors

Sleepwalking is much more common in children than adults and is more likely to occur if a person is deprived of sleep.

People afflicted with this do not experience the normal paralysis that occurs when someone enters REM sleep. People with RBD act out dreams that are vivid, intense, and violent.

Sleep paralysis is a phenomenon in which an individual, during the transitional state between wakefulness and sleep, briefly experiences an inability to move, speak, or react.

Confusional arousal or sleep drunkenness is considered a parasomnia. This category of sleep disorder involves abnormal movements, behaviors, emotions, perceptions, and dreams that occur during all stages of sleep.

A nightmare is a dream occurring during rapid eye movement (REM) sleep that involves strong feelings of terror, distress or extreme anxiety.

The Sleep Center Experience

american academy sleep medicine logo

A sleep study in a sleep center accredited by the American Academy of Sleep Medicine is the best way to identify a sleep disorder. Sleep centers analyze many different symptoms that may relate to a sleep disorder including difficulty falling asleep, chronic snoring, excessive fatigue or falling asleep during the day, pauses in breathing while sleeping, or one of several other sleep-related disorders.

Going to a sleep center can help determine the cause(s) of your problem. What exactly is a sleep study? Do you need to prepare in advance for it? How does the center determine and analyze your condition?

Types of In-lab Sleep Studies

Sleep clinics offer several different types of sleep studies.

Polysomnogram (PSG): An overnight sleep study that records brain activity, breathing patterns, eye movements, heart rate, blood pressure, blood oxygen levels, muscle activity, and more. The results are used to help diagnose some of the following:

  • Obstructive and central sleep apnea (OSA).
  • Seizure disorders.
  • Periodic limb movement disorder (PLMD).
  • Sleep-related disorders caused by excessive daytime sleepiness.

Maintenance of Wakefulness Test (MWT):An MWT will determine how alert you are during the daytime, including your ability to remain awake. Most doctors perform a PSG first, then perform an MWT to determine if your sleepiness is a safety concern. Companies and government agencies most often use the results of these studies to ensure that it is safe for drivers or pilots to operate trucks, cars, planes, buses, and trains.

Multiple Sleep Latency Test (MSLT): the standard measurement doctors use to diagnose narcolepsy and excessive sleepiness that is not caused by sleep apnea or another sleep disorder. MSLT testing generally follows a Polysomnogram and consists of a series of daytime naps that measures how long it takes the patient to fall asleep.

CPAP Titration: A test used to determine optimal positive airway pressure (PAP) settings. If you use the right PAP settings, you will eliminate almost 100% of all apnea events. You wear a mask and the CPAP machine blows air along a tube, into the mask to the back of your throat. The air pressure coming in through the mask is changed to find the optimal PAP settings. With the proper air flow, you should not wake up during the night.

Bi-level or BiPAP Titration: For patients already diagnosed with obstructive sleep apnea, but finding the right continuous positive airway pressure (CPAP) has been difficult, a BiPAP should be considered. For many patients, the bi-level PAP often is more effective. A bi-level PAP has two pressure settings: the standard high-pressure setting for inhalation (IPAP), and a lower pressure setting for when you exhale (EPAP).

Preparing for a Sleep Study

Sleep is a complicated process. The brain controls the various stages of sleep. These stages of consist of deep sleep, drowsiness, dream sleep, and light sleep.

man on his back during a sleep study

The best way to analyze sleep is during an overnight sleep study. It will show in very precise detail exactly what happens while the patient is sleeping. The test results will identify the cause of the sleep problem and allow a sleep specialist to determine which treatment is best.

Avoid caffeinated drinks or alcohol in the afternoon or evening before an overnight sleep study. Try not to take any naps on your test day.

Before going to the sleep center, wash your hair with shampoo only. Do not apply any hair sprays, oils, or gels. If used, they could interfere with the sensors during the study.

Bring an overnight bag with some comfortable pajamas, clothes for the next day, and your toiletries. Do not forget to tell the sleep technician of any prescription or non-prescription medications you may be taking. Certain medications can not only affect your sleeping pattern but also can affect the study’s findings.

Ensure you have eaten dinner and you are ready to go to bed. If you have special needs or concerns, advise the sleep center staff ahead of time. Most sleep clinics want you to go about your usual nightly routine. If you over-prepare or deviate from your normal routine, the results may not be as accurate.

What Happens During an Overnight Sleep Study?

While there may be some variation in procedures at different sleep centers, the following description represents a typical process.

What Will Happen When I Arrive at The Sleep Center?

You are told to arrive for your sleep study sometime between 5:30 pm and 9:30 pm. A registered polysomnographic technologist (RPSGT) will administer your sleep study.

The RPSGT will review your forms, complete any other paperwork necessary, and discuss with your have you fill out any necessary forms, and discuss with you the details of what happens. In your bedroom, a technologist will show you the sleep study equipment. Be sure to inform him or her of any recent changes in your sleep or any specific problems that you did not already discuss with your doctor.

Prepare for bed the same way you do at home. You can watch television, read or relax until the technologist returns. The medical technician will apply suction cup electrodes to your scalp to measure your brain activity while sleeping.

Your brain activity indicates what stage of sleep you are in at various points during the night. The length of the electrode wires allows you to move around and turn over in bed.

The technician will also tape wire electrodes to your face by your chin and eyes to determine any muscle activity that occurs when you sleep. These electrodes can also detect if you grind your teeth at night and other possible sleep disorders.

The readings from the electrodes by your eyes will measure your eye movements, indicating what stage of sleep you are in at the time. Other test equipment connections may include:

  • Two flexible elastic belts placed around the stomach and chest areas that measure the effort it takes for you to breathe while sleeping.
  • A miniature heat monitor with a nasal cannula that measures your breathing activity.
  • Wire electrodes attached to both legs to measure leg movements and/or muscle activity.
  • A clip on your finger monitors your heart rate and the oxygen in your blood.
  • An EKG monitor with 2-3 leads for heart rate and rhythm measurements.
  • A microphone taped to your throat to detect the sounds of snoring.

The sensors should be comfortable and not be an obstacle to falling asleep. Once you have been hooked up to the various machines, the RSPGT will begin monitoring the data from another room.

They will run a series of tests to calibrate the equipment. When the calibrations are finalized you are free to read or watch TV until your normal bedtime.

Isn’t it difficult to fall asleep in a strange environment with all this machinery hooked up to me?

Sleep centers are designed to be as comfortable and cozy as possible. Unlike the stereotypical hospital room, they are not cold and harshly lit. The rooms are nicely decorated. Most patients fall asleep quickly.

What happens while I am asleep?

The sleep technologist monitors you from a nearby room where the monitors are located. You have plenty of freedom of movement as the sensor wires are designed and long enough to allow you to turn over, sit up, or move around on the bed.

You may be awakened by the technician and asked to turn over so the equipment can monitor your breathing patterns and readouts while sleeping in a different position. Video cameras may record you while you sleep so the doctor can review the footage for unusual movements or behavior.

What if the monitors indicate I suffer from sleep apnea?

If the measurements taken while you are asleep indicate obstructive sleep apnea, the technologist awakens you and will have you wear a fitted mask as part of a positive airway pressure (PAP) test. Some masks cover just your nose, while others cover your nose and mouth.

Some masks have soft silicone tubes called nasal pillows that go directly in your nostrils. The mask produces a steady stream of air that continuously blows into the back of your throat.

There are three kinds of PAP: Continuous positive airway pressure (CPAP), Automatic positive airway pressure (APAP), and Bilevel positive airway pressure (BiPAP). The most common is the CPAP.

The technician will work with you until he or she finds just the right level of air pressure to help you breathe and sleep normally.

What Happens During a Nap Study?

A Multiple Sleep Latency Test (MSLT) may be required the day after your sleep study, to confirm a narcolepsy or hypersomnia condition. The trial begins around 1 ½-3 hours after you wake up from the overnight sleep study. You are given four or five opportunities to take a nap along with two-hour breaks between each nap. The same equipment that monitored you overnight will be used to monitor you during the nap study.

Results Analysis

A typical sleep study produces about 1,000 pages of data, including measured eye movements, brain waves, and breathing patterns. The data analysis is a complex and time-consuming process requiring hours of work from a trained professional. A specialist processes this data, and sends the results to your doctor.

If you go to an accredited sleep center, the center requires the doctor to be a board-certified sleep specialist. Given the large amount of data collected during your study, it takes approximately two weeks for you to get the results.


A sleep study is a reliable, scientific, and painless way to discover why you are not sleeping well. It gives you valuable insight into the process of how you sleep and can provide you with answers. With the results, a sleep specialist can develop a plan of treatment to help you finally get the kind of sleep you want and need.

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