How to Read Your Sleep Study Report: A Simple Guide

After undergoing a sleep study (polysomnography), many patients receive a detailed report filled with medical terms and numbers. Understanding this report can help you better grasp your diagnosis and treatment plan.

This guide will help you understand the key components of a sleep study report in a simple and practical way.

1. Apnea-Hypopnea Index (AHI)

This is the most commonly reported parameter.

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

• Normal: <5

• Mild: 5–15

• Moderate: 15–30

• Severe: >30

AHI helps classify the severity of sleep apnea

2. Oxygen Levels (SpO₂)

Your report will include:

• Average oxygen saturation

• Oxygen desaturation index (ODI)

• Oxygen nadir (lowest level reached)

A lower oxygen nadir indicates more severe physiological impact.

3. Sleep Efficiency

Percentage of time spent asleep compared to time in bed

• Normal: >85%

Low sleep efficiency may indicate:

• Poor sleep quality

• Frequent awakenings

4. Sleep Stages (REM & NREM)

Sleep is divided into:

• N1, N2, N3 (non-REM sleep)

• REM sleep

Important points:

• Reduced REM sleep may affect memory and mood

• Poor deep sleep (N3) affects restoration

5. Arousal Index

Number of times you wake up (briefly) per hour

High arousal index means:

• Fragmented sleep

• Poor sleep quality

6. Type of Events

Your report may classify events as:

• Obstructive apnea

• Central apnea

• Hypopnea

This helps determine the type of sleep disorder

7. Positional Sleep Apnea

Some patients have more events while sleeping on their backs

Your report may indicate:

• Supine AHI vs non-supine AHI

This can influence treatment decisions

8. Periodic Limb Movements (PLMS)

Repetitive leg movements during sleep

May be associated with:

• Sleep disruption

• Daytime fatigue

9. Snoring and Respiratory Events

Reports may include:

• Snoring intensity

• Flow limitation

• Respiratory disturbance index (RDI)

Putting It All Together

A sleep study report is not interpreted using a single parameter like AHI alone.

Sleep specialists consider a combination of:

• Breathing events (AHI, type of events)

• Oxygen levels and desaturation

• Sleep stages and sleep efficiency

• Arousals and sleep fragmentation

• Positional variation

In addition, coexisting medical conditions such as obesity, diabetes, hypertension, or lung disease can significantly influence both the interpretation and the choice of treatment.

Because of this, management decisions are highly individualized and based on the overall clinical picture rather than a single number.

Why Expert Consultation is Important

A detailed review by a sleep specialist ensures:

• Accurate interpretation of your sleep study

• Identification of clinically relevant patterns

• Selection of the most appropriate treatment (CPAP, BiPAP, or alternatives)

Self-interpretation or relying on a single value may lead to inadequate or inappropriate treatment.

Take the Next Step

If you have undergone a sleep study, a specialist consultation is essential to translate your report into an effective, personalized treatment plan tailored to your condition and associated comorbidities.