What Your Sleep Study Results Actually Mean

Why Sleep Study Reports Can Be Confusing

Many patients receive a sleep study report containing unfamiliar terms such as:

AHI
ODI
Oxygen saturation
Desaturation index
Apnoea
Hypopnoea

It can be difficult to know what these numbers actually mean.

What Is AHI?

AHI stands for Apnoea-Hypopnoea Index.

It represents the average number of breathing interruptions per hour of sleep.

Normal

AHI less than 5

Mild Sleep Apnoea

AHI 5–14

Moderate Sleep Apnoea

AHI 15–29

Severe Sleep Apnoea

AHI 30 or higher

An AHI of 30 means breathing is disrupted on average every two minutes throughout the night.

What Is an Apnoea?

An apnoea occurs when airflow stops completely for at least 10 seconds.

These events may last significantly longer.

What Is a Hypopnoea?

A hypopnoea is a partial reduction in airflow associated with oxygen desaturation or arousal from sleep.

Why Oxygen Levels Matter

Sleep studies also measure blood oxygen levels.

Important measures include:

Lowest oxygen saturation
Average oxygen saturation
Time spent below 90%

More severe oxygen desaturation may indicate greater physiological stress.

Is Severity Based Only on AHI?

No.

Two patients with identical AHIs may have very different clinical significance.

We also consider:

Oxygen levels
Symptoms
Cardiovascular risk factors
Daytime sleepiness
Occupation

Why Some Patients With Mild Sleep Apnoea Feel Terrible

AHI does not always correlate perfectly with symptoms.

Some patients with mild disease experience profound fatigue.

Others with severe disease report few symptoms.

Treatment decisions must consider the whole clinical picture.

What Happens Next?

Depending on results, recommendations may include:

CPAP therapy
Weight management
Oral appliances
Positional therapy
Further specialist assessment

A sleep study is only the first step. The goal is understanding what the results mean for your individual health and quality of life

What Your Sleep Study Results Actually Mean