At the Michigan Center for TMJ & Sleep Wellness, we believe that proper treatment begins with a thorough diagnosis. Before you are given an oral appliance or referred for other sleep apnea treatment, we want to determine whether you actually have sleep apnea and characterize its severity. The only reliable way to diagnose sleep apnea is with a sleep study, but many people can have sleep studies performed in the comfort of their own homes.
Sleep Apnea Screening
Before we decide whether a sleep test is appropriate for you, we may use one or more sleep apnea screening tools. These are questionnaires that help us identify the likelihood that you have sleep apnea on the basis of common symptoms or risk factors. The simplest screening tool is the STOP assessment, which consists of just four questions:
- Do you Snore loudly?
- Do you feel Tired or sleepy during the daytime?
- Have you ever been Observed to stop breathing at night?
- Have you been diagnosed with high blood Pressure?
The benefit of this brief questionnaire is that it can be used easily in situations where a person with undiagnosed sleep apnea—which may be 80% or more of sufferers—can be identified before entering situations where sleep apnea poses great risk, such as surgery.
There are other, more complex screening tools for sleep apnea, such as the Berlin Questionnaire, the Pittsburgh Sleep Quality Index, and the Epworth Sleepiness Scale. None of these questionnaires can actually diagnose sleep apnea, but they are useful in pointing out your level of risk.
How a Sleep Study Works
In a sleep study, polysomnography is used to monitor many aspects of your sleep. Polysomnography measures your brain waves, breathing rate, heart rate, oxygen levels in your blood, eye movements, and leg movements. Putting all these measurements together tells us about the overall quality of your sleep as well as whether you have sleep apnea.
Sleep apnea diagnosis is based on the number of times your breathing stops or slows, called your apnea-hypopnea index (AHI), which represents how often these events occur in an hour. Sleep apnea severity is broken into several categories:
- AHI less than 5 means you essentially do not have sleep apnea
- AHI 5 to 15 is considered mild sleep apnea (some symptoms, but low risk)
- AHI 15 to 30 is considered moderate sleep apnea
- AHI over 30 is considered severe sleep apnea (high risk, CPAP is the only recommended frontline treatment)
In addition, the sleep study will tell us how much oxygen you are getting, measured by the oxygen saturation of your blood. Whenever the saturation drops below 90%, there is cause for concern, and if it drops below 80%, it is considered severe.
Where Will Your Sleep Study Be?
Sleep studies can be conducted in a sleep lab or at home. The advantage of a sleep lab study is that more comprehensive equipment can be used to get a more complete picture of your sleep, which can help determine whether you have other sleep problems in addition to or instead of sleep apnea.
Sleep studies at home have the benefit of being less expensive, more comfortable, and more convenient, but sometimes they will not give us all the information we need, and you might be asked to take a sleep study in a sleep lab if the home sleep study is inconclusive.
The home sleep study equipment can also be used to monitor the effectiveness of oral appliance therapy, allowing us to ensure you’re getting the best possible results.