Sleep Study, What Should I Expect?

November 11, 2015

One of the common co-morbid conditions is sleep apnea.  Obstructive sleep apnea is prominent with people that struggle with obesity.  The airway of someone that is obese can become obstructed by large tonsils, enlarged tongue and increased fat in the neck, all pressing on the airway when the pharyngeal (throat) muscles are relaxed with sleep. Before a patient is wheeled into the operating room, it is imperative that the medical team know if the patient has sleep apnea to avoid any complications during their WLS.

Sleep apnea is a serious condition that you may, or may not, even know that you have. The determination of sleep apnea isn't detected from a blood test and can only be checked when the patient is asleep.  The clinical diagnosis of sleep apnea is obtained during a sleep study.

A sleep study, also known as a polysomnogram (PSG), is a test that is performed while you sleep at a sleep center in order to diagnose sleep disorders. This test is used to diagnose various sleep disorders including sleep apnea, periodic limb movement disorder, narcolepsy, and REM behavior disorder.

The daytime studies are the multiple sleep latency test (MSLT) and maintenance of wakefulness test (MWT). MSLT is used to diagnose narcolepsy and other causes of excessive daytime sleepiness. MWT is a test that objectively measures your ability to stay awake, which can infer how sleepy you are.

Sleep studies are performed in a sleep center that is often designed to look like a hotel to make the patient more comfortable. During a sleep study, a technician attaches small sensors called electrodes on your scalp, face, chin, chest, finger, and legs. The scalp and face sensors record your brain activities and eye movements in order to measure the different stages of sleep you go through.

What to expect during a sleep study

A small airflow sensor is attached to your nose to detect a change in breathing. An elastic pressure-sensing belt is also placed around your chest and belly to measure the effort in breathing. The data obtained by these sensors is used to diagnose sleep apnea.

Additional sensors are placed on the legs measure muscle activity and are used to diagnose a disorder known as periodic limb movement.

Electrodes attached to your chest and finger measure your heart rate and the amount of oxygen in your blood. A digital video records your sleep behavior during the night.

Analyzing the sleep study

All the data gathered during the night is downloaded in a computer for analysis. The sleep test data is analyzed after your sleep study and a sleep physician reviews the data to make a diagnosis.

A normal sleep pattern starts with a type of sleep termed non-rapid eye movement (NREM) sleep. In NREM sleep, there are three stages that are simply known as stage one, two, and three. The second type of sleep is rapid eye movement sleep (REM). This is identified by rapid movements of the eye and lack of muscle tone while you are in deep sleep. Most dreams occur in this stage.

The following are different sleep disorders that are diagnosed by sleep studies:

  • Sleep apnea is a condition where your breathing repeatedly stops and disrupts your sleep.
  • Periodic limb movement disorder is when involuntary muscle twitches frequently interrupt your sleep.
  • Narcolepsy is characterized by overwhelming daytime drowsiness, sudden attacks of sleep during the day and disrupted sleep at night.
  • Insomnia is the difficulty of falling or staying asleep or waking too early without being able to go back to sleep. Some forms of insomnia can be diagnosed with a sleep study.
  • REM sleep behavior disorder is identified by acting out your dreams while asleep.

With many patients, losing weight from WLS will resolve the co-morbid condition of sleep apnea.  Getting good quality sleep is important to weight loss and good health.

Photo Credit: Army Medicine



Eskender Beyene, M.D. is the Bluepoint Medical Associates Sleep Director. He is a dedicated member of the sleep community with vast experience in the establishment and running of various health centers. Dr. Beyene strongly believes in patient education and awareness. He takes part in various talks to share knowledge of sleep and the processes of sleep disorder treatments.

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