Fixing my sleep, Part 4: Results of the overnight sleep study

alexander-possingham-209285-unsplashMy next appointment at MedSleep would reveal the results of my overnight sleep study. In the weeks leading up to the appointment, I was worried that they’d tell me they didn’t find anything specific. I kept imagining the conversation:

MedSleep: “Your sleep wasn’t great, but we didn’t see anything in terms of a physical cause. Have you tried melatonin / warm baths / progressive relaxation?”

Me: “YES! SOOOO MANY TIMES! Arghghgh!’ (flees the building)

Fortunately, what happened was very different…As with my initial appointment, I saw Carey Marie, the physician extender*, first. She gave me the fine details of the sleep study (each study can produce over 80 pages of data.)

Despite my night of fragmented sleep, she said, “We did get some sleep data – it wasn’t a total waste of time.” Phew!

“Sleep efficiency” was one thing they looked at — it’s the amount of time you actually sleep while you’re in bed. For example, if you were in bed for 8 hours and slept for the entire time, your sleep efficiency would be 100%.

Carey Marie said my sleep efficiency was “severely reduced” at only 56%. For women my age, it should be 78% to 94%. The amount of time I spent in deep sleep was less than it should have been, too, at only 10.3%; for women my age, 15% – 19% is normal.

Next up were respiratory events, which means either stopping breathing completely (apnea) or breathing shallowly (hypopnea — my specialty, apparently). Sleep specialists measure both of these using the AHI (apnea hypopnea index).  The AHI is the average  number of apneas or hypopneas per hour:

  • No sleep apnea/minimal: AHI of less than 5 per hour
  • Mild: AHI of over 5, but less than 15 per hour
  • Moderate: AHI ≥ 15, but < 30 per hour
  • Severe: AHI ≥ 30 per hour

Each time your breathing stops or becomes too shallow, your brain senses this and goes into panic mode (“Look out, we’re starting to suffocate!”), waking you up just enough to get your breathing going again.

Because you’re asleep, you’re not aware of the starting-to-suffocate part — you think you woke up because you needed to turn over / reposition the pillow / whatever. But, if you were in deep sleep with a good open airway, none of these things would wake you.

Apparently I had an AHI of 6.9. “You mean I’m stopping breathing almost 7 times an hour?” I said.

Carey Marie explained that while I wasn’t actually stopping, my breathing did become extremely shallow – and yes, 6.9 times per hour, on average.

This was so exciting that I had trouble processing it. After all the years of trying every sleep hack you can think of, this was it, the Holy Grail — an actual physical, fixable cause for my insomnia. I almost burst into tears of happiness.

Carey Marie stressed that an AHI of 6.9 is considered mild sleep apnea. Still, for an 8-hour night, that’s about 50 awakenings. No wonder I was always so tired!

Dr. Hoffman then confirmed everything Carey Marie had said, and left with me a prescription for a CPAP (continuous positive airway pressure) device — more on the CPAP in my next post!

Meanwhile, I rushed home to tell my husband and son that my insomnia had been stalked and trapped, and was soon to be (I hoped) eliminated. They were so, so happy for me … and then I finally let myself cry those tears of joy.


** A physician extender is “a health care provider who is not a physician but who performs medical activities typically performed by a physician.” (Definition from Carey Marie has a Master’s in biology and is also a registered polysomnographic sleep technologist.



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