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[CPAP] Wakeful time AHIs vs sleeptime AHIs
#1
Idea 
Wakeful time AHIs vs sleeptime AHIs
I had an "aha" moment last night about my AHI numbers, which I've been trying to bring down for four months now. Besides having sleep apnea. I suffer from insomnia 50% of the time, and I've always suspected that my wakeful time throws off my AHIs. Last nigh I fell asleep instanly and woke up couple hours later, I decided to check my AHI numbers at that point since it was ALL sleep time being considerd; the index number was at a 1.2! Then it hit me,... AHA! my real AHIs may already be at the desired level, it's the wakeful time that throws my number into orbit.
It took me 2 maybe 2.5 hours to fall asleep after that. Later, I took off the mask and finished off the night without it because the leaks and dry mouth keep waking me up. The index reading when I got up was at 23 AHI! ugh! However, most of that was wakeful time, so I don't feel so bad after that.
I plan on repeating this experiment when and if I ever fall asleep instantly again.
I don't use software yet for my cpap evaluation. I wonder if it would help differentiate between wakeful time and sleep time....anyone know?
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#2
RE: Wakeful time AHIs vs sleeptime AHIs
I am new and have no idea what I am talking about, but since this is the internet, that means I fit right in.

It seems the opposite of what you are saying would be the case. The AHI is the number of events per hour (of sleep assumed). So, assume you have 100 events over night. Assume you stayed in bed with the machine recording for 10 hours, then the AHI should be 10. Now, if what you are asking worked, then if the machine realized that you were only asleep for 2 of those 10 hours, the AHI would be 100/2 or 50!

Now, I don't know if CPAP machines can tell when you are asleep, but I don't think so - I think they only know when you turn them on and off. So, if you are getting very high AHI values, and it is measuring the time from when you turn it on to when you turn it off, then the high AHIs would be worse if it only measured when you are actually asleep.

Uh, but then I am a noob, so what do I know?
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#3
RE: Wakeful time AHIs vs sleeptime AHIs
(03-26-2016, 12:17 PM)Earthfuture Wrote: I had an "aha" moment last night about my AHI numbers, which I've been trying to bring down for four months now. Besides having sleep apnea. I suffer from insomnia 50% of the time, and I've always suspected that my wakeful time throws off my AHIs.
I am sorry to hear about the insomnia. I say that as someone who has fought and continues to fight the old insomnia monster.

Quote:Last nigh I fell asleep instanly and woke up couple hours later, I decided to check my AHI numbers at that point since it was ALL sleep time being considerd; the index number was at a 1.2! Then it hit me,... AHA! my real AHIs may already be at the desired level, it's the wakeful time that throws my number into orbit.
It took me 2 maybe 2.5 hours to fall asleep after that. Later, I took off the mask and finished off the night without it because the leaks and dry mouth keep waking me up. The index reading when I got up was at 23 AHI! ugh! However, most of that was wakeful time, so I don't feel so bad after that.
Yep. Normal wakeful breathing patterns can and often are mis-scored by our machines as sleep disordered breathing. The machine makes the assumption that if you are masked up, you must be asleep.

Quote:I don't use software yet for my cpap evaluation. I wonder if it would help differentiate between wakeful time and sleep time....anyone know?
The flow rate (or wave flow) data that shows every breath you take can indeed be useful in pinpointing when you probably fell asleep. Encore, alas, does not make it easy to review the flow rate data. When SH 1.0-beta is released, however, you will be able to use it with your DreamStation. It can also sometimes give you an indication of when you might be awake or very restless in the night, but it's only an indication. In other words, there's nothing definitive in the data that you can point to and say with 100% certainty: I was asleep here and I was awake here.

It takes a while to learn how to read your own flow rate data and pick out the characteristics that let you have some idea of whether you were likely awake or not at a particular point in the night.

There are some things that you can do to make it a bit easier to sort out wake vs sleep time in the flow rate data. Here are some of the things that may work for you once you can look at the flow rate data:
  • If you wake up in the middle of the night and you want it to show up in the data, the easiest thing to do is to turn the machine OFF and then back ON. The OFF/ON cycle will be clearly visible in the data.
  • If you've been lying in bed fighting for sleep for a long time and you want to have evidence in the data that you have been a wake for a while, turn the machine OFF and back ON.
  • Consider getting something like a fit bit that attempts to track sleep/wake by use of an accelerometer to measure your movements while in bed. You can then compare the "restless/wake" periods identified by the fit bit to the flow rate data recorded by the machine. Between the two pieces of data, you can usually get a pretty good idea of when you were most likely awake and when you were most likely asleep.
Questions about SleepyHead?  
See my Guide to SleepyHead
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#4
RE: Wakeful time AHIs vs sleeptime AHIs
(03-26-2016, 12:38 PM)FrankNichols Wrote: The AHI is the number of events per hour (of sleep assumed).
No. The machine's AHI is calculated as:

AHI = (number of events flagged during the night)/(total time the machine was on during the night)

Quote:So, assume you have 100 events over night. Assume you stayed in bed with the machine recording for 10 hours, then the AHI should be 10. Now, if what you are asking worked, then if the machine realized that you were only asleep for 2 of those 10 hours, the AHI would be 100/2 or 50!
If you run the machine for 10 hours with the mask on your nose, the machine will assume that you were asleep for 10 hours. It doesn't matter if you were actually asleep 10 hours or 2, the machine is still going to calculate the AHI as 100/10 = 10.

CPAP machines do NOT have a way to determine when we are awake or asleep. And except for the Icon+ with its SenseAwake settings, they don't try to determine whether we're awake or asleep.


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See my Guide to SleepyHead
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#5
RE: Wakeful time AHIs vs sleeptime AHIs
(03-26-2016, 02:38 PM)robysue Wrote:
(03-26-2016, 12:38 PM)FrankNichols Wrote: The AHI is the number of events per hour (of sleep assumed).
No. The machine's AHI is calculated as:

AHI = (number of events flagged during the night)/(total time the machine was on during the night)

Quote:So, assume you have 100 events over night. Assume you stayed in bed with the machine recording for 10 hours, then the AHI should be 10. Now, if what you are asking worked, then if the machine realized that you were only asleep for 2 of those 10 hours, the AHI would be 100/2 or 50!
If you run the machine for 10 hours with the mask on your nose, the machine will assume that you were asleep for 10 hours. It doesn't matter if you were actually asleep 10 hours or 2, the machine is still going to calculate the AHI as 100/10 = 10.

CPAP machines do NOT have a way to determine when we are awake or asleep. And except for the Icon+ with its SenseAwake settings, they don't try to determine whether we're awake or asleep.

I am pretty sure we said the same thing. The definition of AHI actually does say events per hour of SLEEP. The machine as you said (and I did in quotes) assumes you are asleep while the machine is turned on. So, it can only calculate the AHI as events while the machine is turned on.

As I said, based on the OP question, if the machine somehow knew how many hours the OP was asleep, say by turning it off when they woke up and on again just before falling back to sleep, then the calculated AHI would be higher since the number of events per hour of sleep/run time would the higher.

I also stated I did not believe the machines have the ability to know if you are asleep, so what the OP asked would not work. The OP was under the impression that if somehow they could let the machine know that they were awake for part of the night, that information would result in a lower AHI and my comment was to say it would result in a higher AHI (assuming the same number of events were recorded.)
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#6
RE: Wakeful time AHIs vs sleeptime AHIs
(03-26-2016, 12:17 PM)Earthfuture Wrote: I had an "aha" moment last night about my AHI numbers, which I've been trying to bring down for four months now. Besides having sleep apnea. I suffer from insomnia 50% of the time, and I've always suspected that my wakeful time throws off my AHIs. Last nigh I fell asleep instanly and woke up couple hours later, I decided to check my AHI numbers at that point since it was ALL sleep time being considerd; the index number was at a 1.2! Then it hit me,... AHA! my real AHIs may already be at the desired level, it's the wakeful time that throws my number into orbit.
It took me 2 maybe 2.5 hours to fall asleep after that. Later, I took off the mask and finished off the night without it because the leaks and dry mouth keep waking me up. The index reading when I got up was at 23 AHI! ugh! However, most of that was wakeful time, so I don't feel so bad after that.
I plan on repeating this experiment when and if I ever fall asleep instantly again.
I don't use software yet for my cpap evaluation. I wonder if it would help differentiate between wakeful time and sleep time....anyone know?

I have the same problem, I have had Sleep Wake Junk (SWJ)score my AHI in a sleep session as high as 21.4. Therefore, I ran several experiments for 1hour with the mask on during the day-AWAKE
* Watching TV in the recliner
* Surfing the net @ my desk
* Reclined on the sofa reading
* Lying in bed meditating

I got AHI's anywhere from 41.6-85. I analyzed flagged events in sleepy head and ResScan verifying the time I knew I was a wake.

After making offset adjustments to the clock error in the software. I t compare my experimental flagged events to the Flow Rate and Flow limitations Data sets to identify the sleep sessions with the most SWJ. I exported the Data for those nights vis the CSV wizard in sleepyhead and separated our the SWJ form the real events in a spreadsheet / scatted diagram.

It is unfortunate that neither the sleep study folks or the CPAP manufactures have attempted to refine their method to do this. Since insomnia and SWJ clearly skew the numbers.

I recommend getting sleepyhead and the software for your machine and doing some comparative analysis.

I told my DR that my AWAKE apnea appears to be worse then my sleep APNEAOh-jeez





2004-Bon Jovi
it'll take more than a doctor to prescribe a remedy

Observations and recommendations communicated here are the perceptions of the writer and should not be misconstrued as medical advice.
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#7
RE: Wakeful time AHIs vs sleeptime AHIs
(03-26-2016, 03:14 PM)0rangebear Wrote:
(03-26-2016, 12:17 PM)Earthfuture Wrote: I had an "aha" moment last night about my AHI numbers, which I've been trying to bring down for four months now. Besides having sleep apnea. I suffer from insomnia 50% of the time, and I've always suspected that my wakeful time throws off my AHIs. Last nigh I fell asleep instanly and woke up couple hours later, I decided to check my AHI numbers at that point since it was ALL sleep time being considerd; the index number was at a 1.2! Then it hit me,... AHA! my real AHIs may already be at the desired level, it's the wakeful time that throws my number into orbit.
It took me 2 maybe 2.5 hours to fall asleep after that. Later, I took off the mask and finished off the night without it because the leaks and dry mouth keep waking me up. The index reading when I got up was at 23 AHI! ugh! However, most of that was wakeful time, so I don't feel so bad after that.
I plan on repeating this experiment when and if I ever fall asleep instantly again.
I don't use software yet for my cpap evaluation. I wonder if it would help differentiate between wakeful time and sleep time....anyone know?

I have the same problem, I have had Sleep Wake Junk (SWJ)score my AHI in a sleep session as high as 21.4. Therefore, I ran several experiments for 1hour with the mask on during the day-AWAKE
* Watching TV in the recliner
* Surfing the net @ my desk
* Reclined on the sofa reading
* Lying in bed meditating

I got AHI's anywhere from 41.6-85. I analyzed flagged events in sleepy head and ResScan verifying the time I knew I was a wake.

After making offset adjustments to the clock error in the software. I t compare my experimental flagged events to the Flow Rate and Flow limitations Data sets to identify the sleep sessions with the most SWJ. I exported the Data for those nights vis the CSV wizard in sleepyhead and separated our the SWJ form the real events in a spreadsheet / scatted diagram.

It is unfortunate that neither the sleep study folks or the CPAP manufactures have attempted to refine their method to do this. Since insomnia and SWJ clearly skew the numbers.

I recommend getting sleepyhead and the software for your machine and doing some comparative analysis.

I told my DR that my AWAKE apnea appears to be worse then my sleep APNEAOh-jeez

This is very interesting, you are having awake Apnea's? I was not aware that could happen. Are they real events or is it the machine misinterpreting your breathing while you are awake?
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#8
RE: Wakeful time AHIs vs sleeptime AHIs
(03-26-2016, 03:19 PM)FrankNichols Wrote:
(03-26-2016, 03:14 PM)0rangebear Wrote:
(03-26-2016, 12:17 PM)Earthfuture Wrote: I had an "aha" moment last night about my AHI numbers, which I've been trying to bring down for four months now. Besides having sleep apnea. I suffer from insomnia 50% of the time, and I've always suspected that my wakeful time throws off my AHIs. Last nigh I fell asleep instanly and woke up couple hours later, I decided to check my AHI numbers at that point since it was ALL sleep time being considerd; the index number was at a 1.2! Then it hit me,... AHA! my real AHIs may already be at the desired level, it's the wakeful time that throws my number into orbit.
It took me 2 maybe 2.5 hours to fall asleep after that. Later, I took off the mask and finished off the night without it because the leaks and dry mouth keep waking me up. The index reading when I got up was at 23 AHI! ugh! However, most of that was wakeful time, so I don't feel so bad after that.
I plan on repeating this experiment when and if I ever fall asleep instantly again.
I don't use software yet for my cpap evaluation. I wonder if it would help differentiate between wakeful time and sleep time....anyone know?

I have the same problem, I have had Sleep Wake Junk (SWJ)score my AHI in a sleep session as high as 21.4. Therefore, I ran several experiments for 1hour with the mask on during the day-AWAKE
* Watching TV in the recliner
* Surfing the net @ my desk
* Reclined on the sofa reading
* Lying in bed meditating

I got AHI's anywhere from 41.6-85. I analyzed flagged events in sleepy head and ResScan verifying the time I knew I was a wake.

After making offset adjustments to the clock error in the software. I t compare my experimental flagged events to the Flow Rate and Flow limitations Data sets to identify the sleep sessions with the most SWJ. I exported the Data for those nights vis the CSV wizard in sleepyhead and separated our the SWJ form the real events in a spreadsheet / scatted diagram.

It is unfortunate that neither the sleep study folks or the CPAP manufactures have attempted to refine their method to do this. Since insomnia and SWJ clearly skew the numbers.

I recommend getting sleepyhead and the software for your machine and doing some comparative analysis.

I told my DR that my AWAKE apnea appears to be worse then my sleep APNEAOh-jeez

This is very interesting, you are having awake Apnea's? I was not aware that could happen. Are they real events or is it the machine misinterpreting your breathing while you are awake?

My Doctor say everyone has them but there not dangerous because your awake, unless they cause O2 desaturations. He has me wearing a wristband pulse oximeter for 30days to collect data. I did not show any desaturation in his office (awake) or during my sleep tests (mostly awake)
2004-Bon Jovi
it'll take more than a doctor to prescribe a remedy

Observations and recommendations communicated here are the perceptions of the writer and should not be misconstrued as medical advice.
Post Reply Post Reply
#9
RE: Wakeful time AHIs vs sleeptime AHIs
(03-26-2016, 02:56 PM)FrankNichols Wrote: I am pretty sure we said the same thing. The definition of AHI actually does say events per hour of SLEEP. The machine as you said (and I did in quotes) assumes you are asleep while the machine is turned on. So, it can only calculate the AHI as events while the machine is turned on.

As I said, based on the OP question, if the machine somehow knew how many hours the OP was asleep, say by turning it off when they woke up and on again just before falling back to sleep, then the calculated AHI would be higher since the number of events per hour of sleep/run time would the higher.
Except that he has evidence that the vast majority of the events are being recorded while he is awake. Hence they would not be scored on a PSG because they are not sleep disordered breathing.

To continue with you example.

Let's suppose the machine scores 100 events in 10 hours of usage. So the machine AHI is indeed 100/10 = 10.

Now let's assume that 95 of those 100 events are scored during the 8 hours the person is wide awake and using the machine. And hence 5 of the events are actually scored during the 2 hours of sleep. The correct AHI (as scored on a PSG) would be 5/2 = 2.5. Which is quite a bit less than the machine scored AHI = 10. Now I agree that there's no way of making the machine or software do the adjustment automatically---short of repeatedly hitting the OFF/ON button every 10 minutes or so when you awake so that you have a whole lot of short sessions that you can tell SH to ignore.

However, I read as the OP's original question as this: Is there a way to determine with some accuracy when you are awake and when you are asleep with the PAP so that you can "throw out" the events that are flagged when you are awake and then manually compute a more reasonable estimate of the true treated AHI based on the time you actually were asleep?
Questions about SleepyHead?  
See my Guide to SleepyHead
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#10
RE: Wakeful time AHIs vs sleeptime AHIs
(03-26-2016, 04:25 PM)robysue Wrote:
(03-26-2016, 02:56 PM)FrankNichols Wrote: I am pretty sure we said the same thing. The definition of AHI actually does say events per hour of SLEEP. The machine as you said (and I did in quotes) assumes you are asleep while the machine is turned on. So, it can only calculate the AHI as events while the machine is turned on.

As I said, based on the OP question, if the machine somehow knew how many hours the OP was asleep, say by turning it off when they woke up and on again just before falling back to sleep, then the calculated AHI would be higher since the number of events per hour of sleep/run time would the higher.
Except that he has evidence that the vast majority of the events are being recorded while he is awake. Hence they would not be scored on a PSG because they are not sleep disordered breathing.

To continue with you example.

Let's suppose the machine scores 100 events in 10 hours of usage. So the machine AHI is indeed 100/10 = 10.

Now let's assume that 95 of those 100 events are scored during the 8 hours the person is wide awake and using the machine. And hence 5 of the events are actually scored during the 2 hours of sleep. The correct AHI (as scored on a PSG) would be 5/2 = 2.5. Which is quite a bit less than the machine scored AHI = 10. Now I agree that there's no way of making the machine or software do the adjustment automatically---short of repeatedly hitting the OFF/ON button every 10 minutes or so when you awake so that you have a whole lot of short sessions that you can tell SH to ignore.

However, I read as the OP's original question as this: Is there a way to determine with some accuracy when you are awake and when you are asleep with the PAP so that you can "throw out" the events that are flagged when you are awake and then manually compute a more reasonable estimate of the true treated AHI based on the time you actually were asleep?

Once again I completely agree with you and confess I missed the point of events occurring while the user is awake. In fact as noob, I was not aware that you could have events while awake, which changes everything I said.

Thank you for pointing that out.

PS. This then also relates to another thread discussing whether or not there are inexpensive ways to accurately determine if you are asleep and what level of sleep you are at.

Such devices are available - to some degree of accuracy. Namely DIY brainwave monitoring devices. I myself built one a while back based on a Raspberry PI and it was used for brain stimulation and monitoring experiments - the entire cost was under $100. If such a device were generally available (and safe - sigh that is the hard part) would it be reasonable to incorporate that data (time date and sleep level indicator) into sleepyhead?
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