Sleep Study - Why Only One Night of Data?

I've always wondered about this, but keep forgetting to post this question here.

When I got my take-home equipment for my sleep study, I was a little surprised that the sleep department only needed a single night's worth of data to make a sleep apnea determination/diagnosis. As a "data guy" myself, I would have expected that you would need multiple data points to draw any valuable conclusion/diagnosis.

We've all had good nights and bad nights. Is one single night really good enough? And if so, why?

What if you fall asleep and do not have a heavy "apnea" night? Or what if you never have any apnea problems, but it just so happens that the night that you take the test, you had an unusual night's sleep?

Just a question. I've always been curious about this, and the stars aligned to remember to post this here.

Thanks.

MikeekiM wrote: ↑

Wed Mar 06, 2024 6:10 pm

What if you fall asleep and do not have a heavy "apnea" night?

Then you have a diagnosis of sleep apnea, the doctor will write a script and insurance will approve.

MikeekiM wrote: ↑

Wed Mar 06, 2024 6:10 pm

Or what if you never have any apnea problems, but it just so happens that the night that you take the test, you had an unusual night's sleep?

Unusual in what way? Why would you have apneas the night of the study and never again?

If you are going to worry, worry about having apnea and getting a negative result. That would be the worst case.

MikeekiM wrote: ↑

Wed Mar 06, 2024 6:10 pm

(snip)
We've all had good nights and bad nights. Is one single night really good enough? And if so, why?
(snip)

Yes... if you have no issues like O2 desaturation during the night your apnea is probably mild to < mild. Normally during a lab sleep study they tell you to start on your back... the worst position for apneas... I've never had a home study so I don't know what instructions you got.

I've also heard of 3-night home sleep studies... not sure of the utility here... unless it's for a position of responsibility like truck driving or airline piloting to be *absolutely* sure you're OK.

Once you get a diagnosis then it's time for you to take charge... your doctor only wants to see smiley faces on your machine, < 5 treated AHI. It's up to you to make sure the quality of treatment is as good as it can get.

ChicagoGranny wrote: ↑

Wed Mar 06, 2024 6:45 pm

MikeekiM wrote: ↑

Wed Mar 06, 2024 6:10 pm

What if you fall asleep and do *****not***** have a heavy "apnea" night?

Then you have a diagnosis of sleep apnea, the doctor will write a script and insurance will approve.
(snip)
If you are going to worry, worry about having apnea and getting a negative result. That would be the worst case.

Uh, that's the concern cited in the OP as I read it, CG... emphasis added above.

vandownbytheriver wrote: ↑

Thu Mar 07, 2024 8:48 am

MikeekiM wrote: ↑

Wed Mar 06, 2024 6:10 pm

(snip)
We've all had good nights and bad nights. Is one single night really good enough? And if so, why?
(snip)

Yes... if you have no issues like O2 desaturation during the night your apnea is probably mild to < mild. Normally during a lab sleep study they tell you to start on your back... the worst position for apneas... I've never had a home study so I don't know what instructions you got.

I've also heard of 3-night home sleep studies... not sure of the utility here... unless it's for a position of responsibility like truck driving or airline piloting to be *absolutely* sure you're OK.

Once you get a diagnosis then it's time for you to take charge... your doctor only wants to see smiley faces on your machine, < 5 treated AHI. It's up to you to make sure the quality of treatment is as good as it can get.

ChicagoGranny wrote: ↑

Wed Mar 06, 2024 6:45 pm

MikeekiM wrote: ↑

Wed Mar 06, 2024 6:10 pm

What if you fall asleep and do *****not***** have a heavy "apnea" night?

Then you have a diagnosis of sleep apnea, the doctor will write a script and insurance will approve.
(snip)
If you are going to worry, worry about having apnea and getting a negative result. That would be the worst case.

Uh, that's the concern cited in the OP as I read it, CG... emphasis added above.

Yup, and it's less of a real "concern" for me than it is a curiosity.

My wife has complained about my massive snoring for decades. My kids who have slept in the same bed as me in hotels during vacations have told me that it freaks them out when I stop breathing. I clearly have had a lifelong problem with sleeping and sleep apnea, and I have been diagnosed and am finally (after 18 months of battling CPAP usage) getting some quality sleep. So the sleep study worked for me, and got me where I need to be with the diagnosis and treatment. That's a win for me.

My question is really just an academic curiosity of why a single data point (one night) is enough for the diagnosis, and whether something can be missed. As an example, a person with an apnea problem that simply had a good night (and uneventful) night of sleep on the day of their sleep study. Perhaps the answer is: that doesn't happen. But it was always a curiosity for me why Kaiser sent me home and didn't ask me to gather 3-5 nights of data before returning the machine, instead of just the single night.

If a single night's worth of data is diagnostic then there is no need for further nights.

Now if a single night isn't diagnostic then further detective work is needed.

Pugsy wrote: ↑

Thu Mar 07, 2024 10:31 am

If a single night's worth of data is diagnostic then there is no need for further nights.

Now if a single night isn't diagnostic then further detective work is needed.

Good point. A single night can confirm it. Is there any chance of false positive?

But a single night may not be enough to disqualify it, and could be a false negative.

MikeekiM wrote: ↑

Thu Mar 07, 2024 11:38 am

Is there any chance of false positive?

Extremely doubtful since there is some specific criteria that needs to be met that is really hard to fake.
Plus remember.....we are taking a sleep study because of some unwanted symptoms we are having.

I have seen reports of false positives when the test done was a home study that didn't measure actual sleep and perhaps something happened when a person was awake that caused some false positive flagging but those are extremely rare.

For a sleep study done in a lab with tech in attendance....they are going to be able to know for sure if a person was asleep or not.
Not much chance of a false positive then.

MikeekiM wrote: ↑

Thu Mar 07, 2024 10:23 am

(snip)
My question is really just an academic curiosity of why a single data point (one night) is enough for the diagnosis, and whether something can be missed.
(snip)

Sleep apnea severity is usually position-dependent... flat on your back is much worse than side-sleeping. So you could be moderate to severe, yet go in (or do a home one) and not get on your back. All sleep studies should start you flat on your back! Wearables are coming that will revolutionize the diagnosis and treatment btw.

All humans sleep, and no human sleeps perfectly.

But in the context of evaluating a likely-OSA-sufferer, the real purpose of most home sleep tests these days is simply to look for some/any indication that PAP therapy may be helpful to the person. If that indication is not found in the home sleep test, it is time for the likely-OSA-sufferer to get a lab/center NPSG for a more detailed and more reliable evaluation of sleep-breathing and sleep in general.

Therefore, from a patient's point of view, we simply hope the test earns us the right to try PAP therapy to see if it helps with our symptoms, our safety, and our long-term health.

Few things in life are as vital as good breathing and good sleep.

What if you fall asleep and do not have a heavy "apnea" night?

Sorry, I took the emphasis to be on "heavy" - had apnea but not heavy apnea. You guys corrected me.

A famous sleep doctor wrote that false negatives are somewhat common and require an additional night(s) in the sleep lab. Later, he posted that false negatives are rare. So, I don't know.

Thanks for everyone's input. I think my academic curiosity has been satisfied.

Like I said, I am on CPAP/APAP therapy now, and am not bothered by anything or concerned about anything.

I just had an intellectual curiosity about why sleep reports are based on a single night. And this discussion thread was valuable and much appreciated.

But in the context of evaluating a likely-OSA-sufferer, the real purpose of most home sleep tests these days is simply to look for some/any indication that PAP therapy may be helpful to the person. If that indication is not found in the home sleep test, it is time for the likely-OSA-sufferer to get a lab/center NPSG for a more detailed and more reliable evaluation of sleep-breathing and sleep in general.

WHY? There are studies validating home sleep tests. When the diagnosis is OSA, you don't need an in-lab follow-up test to say "yes, you have OSA and need PAP". Now some people don't respond well to the treatment, THAT's an indicator that an in-lab study may pinpoint other factors. But people who show significant improvement with PAP not only in AHI but also in symptoms, really don't need an in lab study. It doesn't make financial sense.

And for @MikeekiM, it makes a lot of sense to do a home titration over several nights than an in-lab titration, because it gives you time to get used to the mask and to determine optimal pressures in your actual sleep setting, rather than the artificial conditions of a sleep lab. Again, if you are using PAP consistently and not seeing improvement, then an in-lab testing and titration makes sense.

Janknitz wrote: ↑

Thu Mar 07, 2024 3:36 pm

WHY?

Because the AASM says so.

Home sleep tests are useful when positive only. "Negative" from a home sleep test is basically the same as "inconclusive" when someone is obviously symptomatic and needs accurate diagnosis of sleep difficulties.

That is not a knock against home sleep testing. Many medical tests are like that. It just means one home sleep test that is negative or inconclusive (often a distinction without a difference) shouldn't be misused by a lazy doc to tell a patient that his home sleep test 'proved without a doubt' that he cannot benefit from PAP. That's not what home sleep tests are for, when used responsibly by experienced, educated doctors.

Or in the exact words of the 2017 AASM guidelines/recommendations:

"We recommend that if a single home sleep apnea test is negative, inconclusive, or technically inadequate, polysomnography be performed for the diagnosis of OSA. (STRONG)"--https://pubmed.ncbi.nlm.nih.gov/28162150/

I am not aware of any strong update to that position, if there is one.

And the reasons for the position are directly related to the crux of the OP's valid basis for curiosity, IMO.

It is fallacy to believe that all useful medical tests are capable of producing definitive negatives. A test for a likely moderate-to-severe-OSA person is useful, but possible mild OSA and possible hypoventilation issues still matter and should not be ignored, discounted, or swept under the rug.

End of my rant.