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By: Rita Brooks on November 22nd, 2017

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5 Types of Sleep Tests and When to Use Them

Sleep Medicine

Many people aren't getting the adequate amount of sleep required for their bodies to function properly. While some individuals just need more sleep because of family, social, or work obligations impacting their shut-eye, others may have an untreated sleep disorder that keeps them from getting good quality sleep each night.

If your patient suspects they have a sleep disorder, a sleep study is generally their first step to a diagnosis. There’s significant value in sleep studies. Most importantly, they provide patients the proper sleep disorder diagnosis so they can begin treatment and improve the quality of their lives.

It’s essential that you're knowledgeable about the types of sleep study tests available and their purpose. Below are five such tests.

1. Polysomnogram (PSG)

A polysomnogram will be administered to your patient if there's suspicion of a sleep disorder and they require a sleep study for diagnosis in order to start treatment.

What is a Polysomnogram?

A PSG is a diagnostic tool used to determine if your patient has a sleep disorder. This test is conducted overnight at the sleep center or hospital.

This test monitors your patient's sleep cycles and stages to identify any disturbances caused by their sleep disorder. Your patient will be connected to a variety of equipment to help monitor things like their:

  • Brain activity
  • Breathing activity
  • Muscle activity

Through a PSG, you document the disorder your patient is suffering from.

Who Are the Best Candidates for a Polysomnogram?

The best candidates for a PSG are patients who may have a sleep disorder, such as obstructive sleep apnea (OSA). This is a disorder where the patient has repeated apnea events or an upper airway obstruction that reduces or blocks airflow during sleep.

Diagnoses That Come from a Polysomnogram

A polysomnogram is used to diagnose a wide range of sleep disorders such as:

  • Central sleep apnea, OSA, sleep-related hypoventilation disorders, and other sleep-related breathing disorders.
  • REM behavior disorder, or other parasomnias (abnormal actions or behaviors while sleeping).
  • Idiopathic hypersomnia, narcolepsy, and other hypersomnolence disorders.
  • Non-24-hour sleep-wake syndrome, delayed sleep phase syndrome (DSPS), or advanced sleep phase syndrome and other circadian rhythm sleep-wake disorders.
  • Bruxism, periodic limb movement disorder (PLMD), restless legs syndrome (RLS), and other sleep-related movement disorders.

2. Multiple Sleep Latency Test (MSLT)

MSLTs are used to test for excessive daytime sleepiness and measure how fast your patient falls asleep in a quiet environment in the daytime. This is a test used to diagnose narcolepsy, and idiopathic hypersomnia.

What is a Multiple Sleep Latency Test?

MSLTs are full-day tests consisting of five scheduled naps scheduled two-hours apart. The patient will lie in a bed quietly during each nap trying to go to sleep. The test measures how long your patient takes to fall asleep once the lights go out. Your patient should be woken up after 15 minutes of sleep. If your patient doesn't fall asleep within 20 minutes, the nap trial should be ended.

Your patient's first nap will be scheduled approximately two hours after you wake them from the overnight sleep study. Have them eat a light breakfast around an hour before their first nap trial.

Sensors will be placed on your patient's face, head, and chin to monitor when they are asleep and awake and identify when they're in REM sleep.

Who Are the Best Candidates for a Multiple Sleep Latency Test?

Good candidates for a MSLT are those who struggle with excessive daytime sleepiness where for no apparent reason, they are sleepy during waking hours or in situations, such as while driving or at work, where others are typically more alert and awake.

Diagnoses That Come from Multiple Sleep Latency Tests

A physician uses MSLTs to diagnose narcolepsy or idiopathic hypersomnia in patients. The multiple sleep latency test is essential in patients with suspected narcolepsy.

3. CPAP Titration

Physicians commonly prescribe CPAP (Continuous Positive Airway Pressure) to manage sleep-related breathing disorders like:

  • Obstructive sleep apnea
  • Central sleep apnea
  • Hypoventilation

Once the patient is diagnosed with any of these disorders, they typically undergo a CPAP study before they can be provided with treatment.

What is CPAP Titration?

CPAP titration studies are conducted overnight in the sleep laboratory. During the study, you will monitor your patient's breathing and adjust the CPAP pressure to determine the proper air pressure required to prevent upper airway blockage, eliminating pauses in their breathing while they sleep.

You'll fit your patient with a nasal mask that connects to a tube on a small pressure generating device.  During a CPAP titration you will monitor their sleep just like you would during an in-lab diagnostic sleep study. You'll measure their:

  • Breathing
  • Heart rate
  • Oxygen levels
  • Brain waves
  • Arm and leg movements

You'll change your patient's CPAP pressure remotely as needed during the night. The patient starts at low levels of pressure, which are then gradually increased when events are seen.

A patient may need a CPAP re-titration study if their previous symptoms like snoring, apnea, or daytime sleepiness come back despite their CPAP treatment. This allows for determination of their correct pressure setting.

Who Are the Best Candidates for CPAP Titration?

Patients who are diagnosed with a sleep breathing disorder, like obstructive sleep apnea are good candidates for CPAP titration before they start treatment.

Diagnoses That Come from CPAP Titrations

A board-certified sleep physician reviews the data you collect from the CPAP titration to decide what CPAP treatment level works best for the patient on an ongoing basis.

4. Split Night Study

A split night study is an alternative for patients with severe OSA.  This study diagnoses OSA and titrates CPAP in a single night, reducing time to treatment. 

What is a Split Night Study?

During the first part of the night, you'll perform a polysomnography and follow up the remainder of the night with CPAP titration. The split night study determines your patient's PAP settings during the same night without them having to come back another night for another test.

Who Are the Best Candidates for a Split Study Test?

A split night study is a feasible option for your patients who have severe sleep apnea or who don't want to return for a second night study.

Diagnoses That Come from Split Study Tests

Split-night studies are generally conducted to diagnose suspected OSA.  They're beneficial for your patients who can't complete more than one overnight in-lab test.

5. Maintenance of Wakefulness Test (MWT)

While most sleep study tests work by diagnosing sleep disorders through a PSG, titrating CPAP machines after diagnosing breathing disorders, or monitoring how fast patients fall asleep, this test challenges your patients to stay awake through periodic trials.

What is a Maintenance of Wakefulness Test?

This test is administered over a full day at the sleep clinic and is used to measure how awake or alert your patient is during the day. It also measures if they can stay awake for a certain amount of time in a relaxing, quiet, and stimulation-free environment.

You will give your patients two to four forty-minute trials during the day in a dimly lit and quiet bedroom. You'll have them look forward while sitting still and not doing anything stimulating, such as reading, singing, talking aloud, or pinching themselves, that could keep them awake intentionally.

Two to three hours after your patient's normal wake-up time you'll begin the first trial. Your patient will typically have breakfast about an hour before their first trial and lunch after their second.

Trials are scheduled about two hours apart. Your patients may have a meal, watch TV, read a book, or move freely around the clinic between trials. They should be monitored between trials.

Who Are the Best Candidates for a Maintenance of Wakefulness Test?

You use this test to:

  • Determine if your patient's previous CPAP therapy, medication, or other treatment is successful.
  • To measure your patient's ability to stay awake in those with occupations where inability to remain awake may raise a safety concerns, such as pilots or truck drivers.

Diagnoses That Come from a Maintenance of Wakefulness Test

Following two or four trials, you'll send the data to a sleep physician to review. The results will determine your patient's level of sleepiness in the daytime.

Key Takeaways:

  • People require good sleep for their bodies to function properly.
  • Sleep studies are usually the first step in diagnosing most sleep disorders.
  • Sleep studies monitor your patient's sleep cycles and stages to identify any disturbances related to their sleep disorder.
  • Most sleep studies measure the patient's ability to sleep, except for the maintenance of wakefulness test, which measures their ability to stay awake.