The Split Night Sleep Study: Challenges and Problems



To someone who may be suffering from obstructive sleep apnea (OSA), the two-night overnight/nocturnal polysomnogram (NPSG) plus continuous positive airway pressure (CPAP) Titration Study is considered the “gold standard” of sleep studies.

But what if, for some reason, you are unable to devote two nights at a sleep clinic? For example, an insurance provider may only choose to cover one night, leaving you to pay the full bill for the other. Or you may find it difficult to sleep in the unfamiliar environs of the sleep study center. Or other personal, financial, or work-related issues may make it difficult to commit to the two-day, non-contiguous window required for the NPSG/Titration studies.

A compromise option is available to diagnose and to treat obstructive sleep apnea: the split night sleep study. However, like most compromises, it solves one problems but potentially creates more serious issues, including possibly missing out on gathering the most complete information about your OSA and being unable to asses the correct treatment for your individual sleep impairment.

What is Obstructive Sleep Apnea?


Obstructive sleep apnea (OSA), commonly called sleep apnea, or simply apnea, is a condition that occurs when a person’s upper airway becomes so obstructed during sleep that they actually stop breathing.

 OSA is most often caused by the most natural of all occurrences: when you sleep, all of your muscles relax, including those in your throat. If those throat tissues relax too far, or are heavier than your neck can support, they may end up squeezing your windpipe shut.

Since you are asleep, you are completely unaware that your own neck is choking off your air. Fortunately, our bodies are capable of rescuing us by waking us up every time this occurs: this restores our waking muscle tone, lifts the relaxed muscles off our throats, and allows us to gasp for air successfully. Unfortunately, this interrupts our sleep — and then when we almost immediately fall back into it, the apnea cycle repeats, sometimes hundreds of times in a single night.

OSA is measured by using the Apnea-Hypopnea Index (AHI): an hourly measure of the number of completely blocked instances of breathing (apneas) and partially blocked instances (hypopnea). An apnea lasts at least ten seconds; reduces blood oxygen levels up to 4%; and literally forces a person to be jolted awake by their autonomic nervous system, which interprets a full-blown apnea as being choked to death.

What are Polysomnogram and Titration Studies?

The ideal solution for diagnosing and treating obstructive sleep apnea is to study your sleep for two nights. The first night is to diagnose whether or not you actually suffer from OSA and how severe your condition may be; the second night is to carefully test and calibrate the most effective treatment:

What is a split night sleep study?

split-night sleep study consolidates both polysomnogram and titration sessions into a single night.

What are the limitations and challenges of a split night study?


From many perspectives, the split night sleep study may appear to be the most practical, economical, and efficient means of completing polysomnogram and titration tests. However, before choosing to do a split night study instead of the two-night NPSG + CPAP Titration option, there are several issues to consider.


Most importantly for the patient, an interrupted, incomplete sleep study may give an unfavorable first impression of CPAP therapy. Although a patient in a split-night study will enjoy the benefits of sleeping with a CPAP device to alleviate their apneas, they will only be using it for as little as one or two hours at the end of a long night of sleep study.

In contrast, dedicating a full night for a CPAP titration study allows the sleep technician to test, adjust, and instruct the patient in the first few hours of their sleep period. Once they have determined the best titration level for the patient, they leave them to sleep the rest of the night in apnea-free bliss — which may result in the patient waking the next morning to find themselves surprisingly rested, even with less than a full night’s sleep.

No matter which kind of sleep study you choose, it has been shown through several studies that even an imperfect titration study can effectively treat obstructive sleep apnea. Your doctor may order an additional study if necessary, and can help you with adjusting your CPAP therapy pressure at any time.

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