Breathing During Sleep in Normal Middle-Aged Subjects

[Shin Ryoku]

This study is pretty interesting: https://academic.oup.com/sleep/article-p...130205.pdf

One could argue that some of the study subjects included as "normal" may in fact have had OSAS with underreported symptoms.  Still, it's interesting to see breathing data from a random selection of middle aged people who reported feeling well. 

In particular, the data from the women (who had lower BMI and did not include subjects with BMI > 30) showing a mean AHI of 1.8 was of interest and indirectly supports targeting a lower AHI than just "under 5" in treated individuals.

Does anyone know of any other studies looking at AHI in non-obese, "healthy" volunteers?

[HalfAsleep]

That link expired. Could you maybe state the title?

[Shin Ryoku]

Sorry, link should be fixed now. Otherwise it should be the first result in a Google search for "Breathing During Sleep in Normal Middle-Aged Subjects".

[Shin Ryoku]

This is another study done by the same investigators with data re: respiratory events in "healthy" young (medical student) volunteers: https://academic.oup.com/sleep/article-p...060203.pdf

Unless I am misreading the data, hypopneas are common, especially in REM, in healthy young people. Mean of 0.8 (SEM 0.3) hypopnea events per hour during light slow-wave sleep and 12.8 (SEM 2.8) hypopnea events per hour during REM sleep. Seems like a lot!

[HalfAsleep]

Thanks for the new link(s).

My quick assessment:

The article was published in 1990, and we've learned so much since 1990. Most research about apnea has been undertaken since then, so I would tend to rely on newer research for this topic, with special focus on the last 5 years.

It jumps right off the page that the researchers are committed to correlating incidence of apnea with BMI:  "These "apneic" subjects differed from the "nonapneic" subjects only in that they had a higher body mass index. " This is still a stereotype to this day, but not a current viable finding.  Worse, the lingering idea that OSA is associated with high BMI is dangerous for those with low BMI's and symptoms of sleep disordered breathing, since it inhibits evaluation and treatment.

So, severe subject selection bias in this study.

I stopped reading very quickly....

[Shin Ryoku]

If you know of any newer studies looking at the frequency of respiratory events in "healthy" people who feel "well", I'd love to see it.

In the meanwhile, IMO, one can take some value from the data of that study.  Putting aside any of their generalizations about BMI, we can look at the fact that they recruited people who felt well and considered themselves healthy and looked at how often they were having respiratory events.

Subjects Forty subjects (20 men, 20 women) were recruited in the order in which they replied to a notice in a local newspaper requesting healthy volunteers for sleep studies. Before being allowed to apply, the subjects were informed of the conditions and constraints of the study and reminded of the need for them to be in good health. Particular attention was focused on insomnia, daytime somnolence, and habitual snoring; the applicants then underwent a clinical interview and examination.

The criteria for exclusion, in addition to signs or symptoms of sleep disorders, were the presence of any major organic or psychiatric disease and the use of hypnotics. No subject complained of daytime somnolence or habitual snoring; seven of the men (35%) and four of the women (20%) admitted occasional snoring. Only one subject, who had a major psychiatric disorder treated with neuroleptics, was excluded. All subjects gave written consent.

[Mogy]

Hi Shin Ryoku,
Thanks for the link. It is a very interesting study. It will take me a while to get through  but I agree, it is surprising that the young people in the study had that many hypopneas.

[HalfAsleep]

People frequently underestimate stuff like somnolence, snoring, etc. "Normal" subjects with hypopneas might suggest they aren't "normal".

Selection bias.


I believe this study is fatally-flawed on the merits. The assumptions on which the study is based invalidate the results.

[Shin Ryoku]

People frequently underestimate stuff like somnolence, snoring, etc. "Normal" subjects with hypopneas might suggest they aren't "normal".

Selection bias.


I believe this study is fatally-flawed on the merits. The assumptions on which the study is based invalidate the results.

I cited two different studies, one for middle aged and one for young.  The one with the surprising number of hypopneas was the second link, with the subjects having not been selected in relation to presence or absence of any specified symptoms.

Subjects We studied two groups of subjects. The first, a group of 20 normal medical students, comprised 10 males and 10 females. Their mean age ± SEM was 24 ± 0.5 years; their age range was 20-30 years.

Having known and taught a great many medical students, I was surprised to see such a high frequency and prevalence of hypopneas in that group!

[Shin Ryoku]

It jumps right off the page that the researchers are committed to correlating incidence of apnea with BMI:  "These "apneic" subjects differed from the "nonapneic" subjects only in that they had a higher body mass index. " This is still a stereotype to this day, but not a current viable finding...

The early study which I linked noted an observation of the correlation between apnea and BMI in patients without symptoms.  They did not state that lower BMI patients cannot have apnea, symptomatic or otherwise.


That said, it is even more well established now than it was in 1990 that obstructive apnea is far more prevalent amongst those with high BMI.

Reference: https://www.ncbi.nlm.nih.gov/pmc/article...kws342.pdf