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AHI vs RDI: Why Your Sleep Study Said "Normal" But You're Not

My sleep study came back "MILD OBSTRUCTIVE SLEEP APNEA."

NHS said not significant enough for treatment. I felt dismissed. Again.

Years of exhaustion. Finally got a sleep study. And... nothing.

But I kept digging. Learned about AHI vs. RDI. That's where UARS was hiding.

I'm writing this between Christmas and New Year's. That strange week where time feels suspended. The world is quiet. If you're chronically ill, you know this feeling—the relief of no one expecting anything from you, mixed with the grief of another year struggling. This post is for those of us using these dark, still days to finally understand what's wrong.

What Is AHI?

Apnea-Hypopnea Index (AHI) - what most doctors look at.

Counts:

  • Apneas: Complete breathing stops ≥10 seconds
  • Hypopneas: Partial breathing reductions with oxygen drop ≥3-4%

Severity scale:

  • Normal: Less than 5 events/hour
  • Mild OSA: 5-15/hour
  • Moderate OSA: 15-30/hour
  • Severe OSA: 30+ events/hour

My AHI was just high enough for "mild OSA" diagnosis. NHS said: not significant, no treatment offered.

But I was collapsing. Couldn't function.

What Is RDI?

Respiratory Disturbance Index (RDI) - what they SHOULD look at for UARS.

Counts everything in AHI PLUS:

  • RERAs (Respiratory Effort-Related Arousals)

What's a RERA?

Your airway partially closes → increased effort to breathe → brain wakes you up briefly.

Crucially:

  • No full stop in breathing (not an apnea)
  • No significant oxygen drop (not a hypopnea)
  • BUT: fragments your sleep, prevents deep restorative sleep

This is UARS. And many sleep labs don't score RERAs. They focus on AHI only.

Why I Was Dismissed

First sleep study: AHI qualified me for "mild OSA." But NHS wouldn't treat it.

I researched. Found RDI. Got detailed analysis of my data.

My RDI was HIGH.

Dozens of RERAs per hour. My sleep was fragmented all night. But doctors had only looked at AHI.

That's UARS. That's why I felt terrible despite "mild" diagnosis.

The Pattern

This happens to so many UARS patients:

"My sleep study was normal."
"They said I have mild OSA, not significant."
"Doctor says I'm fine, but I feel terrible."

Translation: Your AHI is low. Your RDI (if they even looked at it) is high. You have UARS, but they're not screening for it.

What to Ask Your Doctor

Don't accept "normal" or "mild" if you're still suffering.

Ask specifically:

  • "What's my RDI, not just my AHI?"
  • "Do you score RERAs on sleep studies?"
  • "Could I have Upper Airway Resistance Syndrome?"

For sleep study:

  • Request RERA scoring
  • In-lab polysomnography is more detailed than home tests
  • If possible: request esophageal manometry (gold standard for UARS, but rare)

Interpreting results:

  • Low AHI + High RDI = likely UARS
  • Ask for detailed breakdown, not just "normal/mild/moderate"

If Your Doctor Dismisses You

This is the part that makes me rage. The medical gaslighting.

"Your AHI is only 6. That's normal. You're fine."

No. I'm not fine. My RDI is 35. I'm having dozens of breathing-related arousals every hour. I never reach deep sleep.

What to do:

  • Push back. Ask specifically about RDI.
  • Request second opinion from sleep specialist who knows UARS.
  • Consider private testing if NHS won't help (I know - expensive, unfair).
  • Print research studies, bring to appointments.
  • Join UARS communities (Reddit r/UARS, Hope2Sleep Facebook group) for support and resources.

You're not making it up. The data exists. They're just not looking at the right metric.

The New Year's Reflection

It's December 27th. That weird liminal space between Christmas and New Year's.

For those of us chronically ill, this time of year is heavy. Another year gone. Still struggling. Watching everyone post their "New Year, New You" goals while you're just trying to survive January.

But here's what I'm learning:

These dark days—the shortest days of the year, the quiet between celebrations—they're not all bad.

There's less pressure. Less noise. The world slows down and for once, our pace doesn't feel wrong.

There's space for hard truths. Like: My sleep study said "mild" but I'm not mild-ly suffering. I'm severely impaired. And it took years to find a doctor who would look at the right numbers.

If you're using these quiet days to research, to understand your body, to prepare to advocate harder in the new year—that's not dramatic. That's survival.

We deserve doctors who look at ALL the data. Who don't stop at AHI. Who understand that "mild" on paper can be devastating in reality.

You Deserve Answers

If your sleep study said "normal" or "mild" but you're suffering, don't accept it.

Ask about RDI. Ask about RERAs. Ask if they're screening for UARS.

You're not making it up. UARS is real. The exhaustion is real. The impact on your life is real.

Keep pushing. You'll find someone who listens.

Start here if you're newly diagnosed: What is UARS?

Understand why treatment isn't always enough: The CPTSD-UARS Connection

Note: I'm not a doctor. This is my personal experience. Consult healthcare providers for your situation.