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Data from a polysomnography performed in a split-night sleep study.

Why Your Doctor Recommends a Split-Night Study

Why Your Doctor Recommends a Split-Night Study

For people living with sleep apnea, just getting through the day can be a challenge. The effects of long-term sleep deprivation continue to get worse and worse as the nights of bad rest add up. For patients with sleep apnea, every night spent without proper treatment is not only exhausting, but also life-threatening.

The first step to successfully treating and managing the symptoms of obstructive sleep apnea is diagnosis. A split-night study is one diagnostic option for moderate to severe OSA. These days, many doctors are recommending this type of test because it has a number of advantages for anyone struggling with a sleeping disorder. Get more information on this overnight test for people with sleep apnea and how it may be beneficial for you.

What Is a Split-Night Study?

If you are at higher risk for obstructive sleep apnea or are showing signs and symptoms of the sleep disorder, your doctor may refer you for a split-night study. There are two basic parts to this overnight analysis.

  1. In the first part of the test, a polysomnogram tracks brain waves, the blood oxygen level, heart rate, breathing, and body movement while the person sleeps. This session lasts at least two hours.
  2. For the second part of the split-night test, the person will use a CPAP (Continuous Positive Airway Pressure) device while sleeping. The sleep technician will monitor its effectiveness and make adjustments to find the right amount of pressure.

What Happens During a Split-Night Study?

Before the clinical sleep test, the technician will review the process and instructions with you. You will also be fitted with a CPAP mask which will be used later. You can try the device out in order to ease the transition into the second part of the test, if needed. Then, you will be hooked up to the testing equipment and encouraged to relax and fall asleep as you normally would.

Next, data is collected in real-time during the first part of the sleep test is used to decide if the second part should be performed. The technician looks for activity that signifies an obstructed upper airway and indicates that CPAP therapy may be appropriate. The American Academy of Sleep Medicine (AASM) has provided clinicians with a standard guideline for identifying good candidates for CPAP therapy.

After a few hours, if certain markers were found, the person will be gently woken up. Then, he or she will utilize a CPAP machine for the second part the split-night test. Once asleep, the technician will perform what is known as CPAP titration. This process requires the tech to slowly increase the CPAP pressure until the disordered breathing activity and snoring has been corrected.

In the morning, the CPAP and testing equipment is removed. At this point, the data from the split-night analysis can be used by the physician to make a diagnosis and create an effective treatment plan.

Who Is a Good Candidate for a Split-Night Study?

Even if your doctor has recommended this type of sleep testing, you may not be a good candidate for CPAP therapy. Clinicians will likely not proceed with the second part of the test if:

  • If the data collected does not show a certain amount of disordered breathing events during the first part of the test. People with mild sleep apnea do not usually qualify for CPAP therapy.
  • If the patient took a long time to fall asleep, not leaving sufficient time to try CPAP therapy and adjust the pressure properly.

One of the most dangerous symptoms of sleep apnea is the ongoing periods when they stop breathing during sleep. This type of ongoing disordered breathing causes an increased risk for major health problems affecting the heart, brain, and immune system. If these apneas occur infrequently, the patient may only have mild sleep apnea and other treatment options would be more appropriate, such as an oral appliance. For moderate to severe sleep apnea in adults, recommended treatment may include using a CPAP device or Inspire sleep therapy.

What Are the Advantages of a Split-Night Study?

A split-night polysomnogram test is an effective way to quickly diagnose moderate to severe OSA in adults. Here are the major benefits of these overnight sleep studies.


For those more high-risk patients, a split-night study can help diagnosis and start treating sleep apnea immediately. Because the two-part process essentially enables clinicians to perform two studies in the same night, the average turnaround time from referral to treatment is shorter. Plus, the technician can calibrate the airway pressure settings to your needs without requiring a second appointment or testing procedure.

Accuracy & Success

Split-night analysis is an accurate diagnostic procedure for OSA and titrating CPAP machines. Patients diagnosed during this test have the same therapy success rates as those diagnosed through a two-night test. Additionally, people are encouraged to try on several masks and get familiar with the CPAP device, which is a crucial first step in ensuring long-term treatment success.


Anyone struggling with sleep apnea knows that even just one night of better-quality sleep is precious. Being able to get a solid diagnosis and begin treatment on the same day, without having an extra appointment in the clinic is a convenient option. It helps patients to start sleeping and feeling better quicker.

Less Expensive

The development of split-night sleep studies has decreased the cost of testing for sleep apnea. They are often less expensive than two, full-night study procedures.

When Is Another Type of Sleep Study Recommended?

Split-night studies may not be for everyone. Other testing process or full-night tests may be recommended by your doctors when:

  • Your disordered breathing activity happens mostly or entirely during the REM period of sleep. Analyzing activity during this sleep stage may require a longer testing period.
  • It takes you a long time to fall asleep. CPAP titration can require a longer period of time than what remains after the first part of the split-night test is complete.
  • Your body position while sleeping influences the degree of apnea activity. If sleeping in the lab changes your regular sleeping position, it may take a full night to gather the data needed for diagnosis.

Learn more about how Sleep Apnea Is a Growing Health Problem.

You Deserve to Feel Rested – Sleep Health Solutions

Whatever type of sleep testing your doctor recommends, our goal is always to help patients reach a diagnosis and identify the best treatment options for you. We want you to have restorative sleep and feel healthier as quickly as possible. Contact Sleep Health Solutions of Ohio for diagnostic sleep testing at (330) 923-0228.

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