What is a split-night sleep study?
A split-night sleep study is an overnight study in a sleep lab that can do two jobs in one night. The first part checks your breathing while you sleep. If it shows moderate to severe obstructive sleep apnea and enough of the night is left, the rest of the night is used to start CPAP and adjust it.1
What happens during a split-night sleep study?
During a split-night sleep study, the first part of the night is used to test your breathing, and the second part may be used to try CPAP. A medical provider orders the study, and you spend the night at a sleep lab. CPAP, short for continuous positive airway pressure, is a machine that sends air through a mask you wear while you sleep.
The switch to CPAP depends on what the first part of the night shows. Under the American Academy of Sleep Medicine (AASM) guideline, both of these must be true:1
- Moderate to severe obstructive sleep apnea shows up during at least 2 hours of recording time.
- At least 3 hours are left in the night to fit and adjust CPAP.
If both are true, you wear CPAP for the rest of the night while the sleep team adjusts the air pressure. This part of the night is called CPAP titration.1
Why do sleep doctors use split-night studies?
Sleep doctors may choose a split-night study because the AASM guideline suggests this approach, if clinically appropriate, instead of a full-night study for diagnosing obstructive sleep apnea in a lab.1 The guideline rates this as a weak recommendation and words it as a suggestion.1
Because the suggestion depends on what is clinically appropriate, your doctor decides whether a split-night study makes sense for you. When the criteria are met, the study fits testing and a first CPAP trial into the same night.1
What if the criteria aren't met?
If the criteria aren't met, the whole night is used for testing instead. The AASM guideline says that when one or both conditions are not met, a full-night diagnostic approach should be used.1
For example, the first part of the night may not show moderate to severe sleep apnea, or fewer than 3 hours may be left for CPAP. In that case, you spend the rest of the night without CPAP while your breathing is recorded. Your doctor will go over the full-night results with you and talk about next steps.
Can a split-night study be done at home?
No, a split-night study is done in a sleep lab. CPAP can be started during an in-lab sleep study, but it cannot be started during a home sleep apnea test.1
A home sleep apnea test is a different kind of test. It lets you sleep at home wearing equipment that collects information about how you breathe, and you usually set it up yourself.2 A medical provider may recommend one if it is highly likely that you have moderate to severe sleep apnea and you have no other significant medical conditions.2
You can learn more in our article on how a home sleep study works. Wesper develops FDA-cleared home sleep testing devices, which are used for home sleep tests and are separate from in-lab split-night studies.
What should you expect that night?
You can expect to sleep at the sleep lab with small sensors placed on your body. The sensors record your brain waves, heartbeats and breathing. They also track your eye, leg and arm movements and the oxygen level in your blood.3
If the first part of the night meets the criteria, a member of the sleep team will help you put on a CPAP mask. You then go back to sleep wearing it while the air pressure is adjusted for the rest of the night.1
Wearing a mask for the first time can feel unfamiliar, and the sleep team can answer your questions. If you would like to learn about CPAP before your study, read our answers to common questions about CPAP therapy.
What happens after a split-night sleep study?
After the study, a sleep technologist scores the recording by marking your sleep stages and any events of abnormal breathing or leg movement.3 This information helps your doctor make a diagnosis and develop a treatment plan.3
Only a medical provider can diagnose sleep apnea, so your doctor will review the results with you.4 Our guide on how to read sleep study results explains the numbers you may see. Our overview of the types of sleep studies shows how in-lab studies and home tests fit together.
Frequently asked questions
Is a split-night study done in a sleep lab?
Yes. A split-night study is a type of in-lab sleep study. CPAP can be started during an in-lab study, but it cannot be started during a home sleep apnea test.1
What if I don't have enough breathing events in the first half?
If the first part of the night does not show moderate to severe sleep apnea, the full night is used for testing instead.1 Your doctor will go over those results with you.
Will I need to try CPAP during the study?
You would try CPAP only if the first part of the night meets the split-night criteria.1 If it does not, you sleep the rest of the night without CPAP while your breathing is recorded.
How is a split-night study different from a home sleep test?
A split-night study takes place in a sleep lab and can include a CPAP trial. A home sleep apnea test is done at home and cannot be used to start CPAP.1
Talk with your doctor or sleep provider about whether a split-night study, a full-night study or a home sleep test fits your situation. They can also tell you how to prepare for your night at the sleep lab.
This article is for general education and is not medical advice. Talk with a licensed medical provider about your symptoms and testing options.
Sources
- Kapur VK, Auckley DH, Chowdhuri S, Kuhlmann DC, Mehra R, Ramar K, Harrod CG. Clinical practice guideline for diagnostic testing for adult obstructive sleep apnea: an American Academy of Sleep Medicine clinical practice guideline. J Clin Sleep Med. 2017;13(3):479-504. aasm.org
- American Academy of Sleep Medicine. Home sleep apnea test. Sleep Education patient page, reviewed August 2020. sleepeducation.org
- American Academy of Sleep Medicine. Sleep study. Sleep Education patient page, reviewed September 2020. sleepeducation.org
- Rosen IM, Kirsch DB, Carden KA, et al. Clinical use of a home sleep apnea test: an updated American Academy of Sleep Medicine position statement. J Clin Sleep Med. 2018;14(12):2075-2077. aasm.org
This article is for general information and is not medical advice. Talk to a healthcare provider about your sleep health.
