How to Interpret Your Sleep Study Results: The Sleep Apnea AHI Scale

The severity of sleep apnea can vary from person to person, but it is a key factor when a healthcare professional considers the most suitable treatment plan for the disorder.

This is where the sleep apnea AHI scale comes into play. A sleep study is used to diagnose sleep apnea, producing an AHI sleep apnea score that helps determine the severity of the disorder. Understanding the sleep apnea AHI scale also helps you better understand how the disorder affects your sleep.

Testing for Sleep Apnea

There are two types of sleep studies used in diagnosing sleep apnea:

  • At-home study: a portable monitor is attached to a clip placed on the finger and records data as you sleep in your home
  • In-lab study: an overnight stay at a sleep clinic where technicians use sensors to monitor your sleep

The studies record various data, including breathing patterns, heart rate, and oxygen levels in the blood. While an at-home test is sufficient for some people, those with more complex medical issues will require a more comprehensive study provided by a sleep clinic.

A key measurement produced by a sleep study is the apnea-hypopnea index, normally abbreviated to the AHI index.

Apnea Versus Hypopnea

The sleep apnea AHI scale measures the severity of a person’s sleep apnea. It is centered around the respiratory events or breathing pauses experienced while you sleep. This is when we first get introduced to apnea versus hypopnea.

  • Apnea: a complete breathing pause caused by obstructed airways that can last for ten seconds or more
  • Hypopnea: partial breathing pauses caused by a narrowing of the airways, where breathing could be reduced by up to 90% of normal levels and snoring is often present

These are the key measurements used in the sleep apnea AHI scale.

Understanding Your AHI Sleep Apnea Score

The severity of sleep apnea is classed as mild, moderate, or severe and is indicated by your AHI sleep apnea score, as reported by a sleep study.

  • AHI score 5 to 15: mild sleep apnea
  • AHI score 15 to 30: moderate sleep apnea
  • AHI score over 30: severe sleep apnea

A score below five on the sleep apnea AHI scale is classified as normal and not considered sleep apnea.

The AHI sleep apnea score is produced by using the following simple equation:

  • AHI = apneas + hypopneas / total hours of sleep

The resulting sleep apnea AHI score signifies the severity of your sleep apnea. This can be used by your healthcare provider to recommend the most suitable treatment plan to help reduce your debilitating sleep apnea symptoms.

Another significant indicator measured in a sleep study is oxygen levels in your blood. Every breathing event caused by sleep apnea results in a fall in the level of oxygen in the blood. This is termed oxygen desaturation and is also included in a sleep study report to help create a broader picture when diagnosing sleep apnea.

Sleep Apnea Symptoms and Severity

Interpreting the results of a sleep study is key, as you may think that the severity of the symptoms is the obvious indicator of the severity of the disorder. This is not, however, the only predictor.

Often the patient remains unaware they are exhibiting some of the primary symptoms of sleep apnea, such as snoring and frequent brief awakenings for air. It can take a sleep partner to first recognize these signs.

Someone with mild sleep apnea as classified by the sleep apnea AHI scale may report more severe symptoms than someone with a severe degree of the disorder.

What is important is recognizing the symptoms. The majority of sleep apnea cases go undiagnosed, placing people at increased risk of serious health issues linked to untreated sleep apnea, including heart disease, stroke, and diabetes.

However, once diagnosed, sleep apnea is managed through treatments like CPAP therapy and lifestyle changes aimed at weight loss if obesity is a contributing risk factor.

Sleep apnea symptoms include:

  • Frequently waking for air
  • Waking gasping for air
  • Snoring
  • Excessive daytime sleepiness
  • Morning headaches
  • Dry mouth
  • Poor concentration
  • Memory issues
  • Mood swings
  • Disrupted sleep patterns

Not everyone with sleep apnea will display all these symptoms, and having one of these symptoms does not mean you automatically have sleep apnea.

However, if you recognize these symptoms, then you should consult your doctor, who may recommend a sleep study. From there, an AHI sleep score will help ascertain an accurate diagnosis.

Can Your AHI Sleep Apnea Score Go Up?

A new sleep study may be recommended if changes are noticed, such as a return of sleep apnea symptoms or weight loss that may warrant lower pressure settings on a CPAP machine.

Your sleep apnea AHI range can also naturally vary within a reasonable level. However, if it increases by a noticeable degree when normally stable, it could indicate an issue that requires further investigation.

Reasons for an increase in your AHI score can include:

  • New medications
  • Leaks from an incorrectly fitting CPAP mask
  • Removing CPAP mask during the night, whether intentionally or unconsciously in your sleep
  • Unexplained excessive changes in your weight
  • Advent of central sleep apnea, where the signals to breathe from the brain temporarily stop

Overall, the sleep apnea AHI scale is an important part of a diagnosis. Your AHI indicates the severity of the disorder, and along with further factors like symptoms, a family history of sleep apnea, and weight, helps your healthcare provider recommend the most suitable treatment plan to reduce your symptoms and improve your sleep quality.