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Why is my AHI worse the last few hours of sleep? - Printable Version

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Why is my AHI worse the last few hours of sleep? - dk2011 - 03-30-2018

I have noticed that several nights now my AHI is much better the first 5 hours of sleep, and horrible the last couple hours.  I've attached my data from last night.  Would anybody be so kind as to take a look at tell me what you think may be causing it?  Could it be my sleeping position?  Because I usually start the night on my back, then I switch to my side?  Or is it something else probably?

Thanks Thanks in advance, you guys are the best!  I'm learning so much!


RE: Why is my AHI worse the last few hours of sleep? - Crimson Nape - 03-30-2018

It does raise the possibility that you are more relaxed the second portion of the night thus causing an increase in flow restrictions.


RE: Why is my AHI worse the last few hours of sleep? - Walla Walla - 03-30-2018

It could be positional. People tend to tuck their chin in more when in the fetal position.


RE: Why is my AHI worse the last few hours of sleep? - Sleeprider - 03-30-2018

It is noteworthy that nearly all of your events are at a pressure less than 9.0.  This might be a message regarding your minimum pressure setting.


RE: Why is my AHI worse the last few hours of sleep? - dmeRT - 03-30-2018

Possible you entered REM sleep.  Majority of REM occurs later on in the sleep cycle.  5 hours in seems about right...


RE: Why is my AHI worse the last few hours of sleep? - dk2011 - 03-30-2018

(03-30-2018, 10:10 AM)Walla Walla Wrote: It could be positional. People tend to tuck their chin in more when in the fetal position.

Sleepy on my back (face up) might be best then?

(03-30-2018, 10:16 AM)Sleeprider Wrote: It is noteworthy that nearly all of your events are at a pressure less than 9.0.  This might be a message regarding your minimum pressure setting.

Should I set my pressure range to 9.0-12.0 then?


RE: Why is my AHI worse the last few hours of sleep? - Ron AKA - 03-30-2018

(03-30-2018, 10:00 AM)dk2011 Wrote: I have noticed that several nights now my AHI is much better the first 5 hours of sleep, and horrible the last couple hours.  I've attached my data from last night.  Would anybody be so kind as to take a look at tell me what you think may be causing it?  Could it be my sleeping position?  Because I usually start the night on my back, then I switch to my side?  Or is it something else probably?

I also have noted that my apnea events seem to occur more towards the morning. As others have noted it may be related to your sleep level being REM or non REM. I believe REM sleep tends to be more frequent towards the morning. This in turn may cause more positional changes. There is a study which found that REM sleep is a contributing factor to obstructive sleep apnea in the lateral (side) sleep position for men. So yes, it could be a combination of having more REM sleep and sleeping on your side toward morning.

OSA During REM Sleep


RE: Why is my AHI worse the last few hours of sleep? - Ron AKA - 03-30-2018

"Should I set my pressure range to 9.0-12.0 then?"

I have looked at a number of your posted results, and would suggest a minimum pressure of 8.0 cm as a first try. What I have found helpful in SleepyHead is to mouse over each OA event. When the event kind of draws a box around it, take note on a piece of paper what the Pressure is just over the Pressure graph. It changes as you move the cursor across the screen. That is the pressure at which the apnea was initiated. Do this for each OA event. Now look at all the pressures you have recorded and compare them to a possible minimum pressure level. In your case say you are considering 8.0 cm. Now make note of how many events have a lower initiation than 8.0. That is your potential improvement if you were to set the minimum at 8.0 cm. The higher you set the minimum the more events you will catch, but at the same time the higher you push the pressure the more uncomfortable it may become. So it is a compromise decision. Like I say, I would try 8.0. Also be aware that when you reduce OA events H (hypopnea) events should reduce too. The H events are the main component of your AHI, but they are not as serious so I would focus on the OA events first.

Hope that helps some,


RE: Why is my AHI worse the last few hours of sleep? - Walla Walla - 03-30-2018

If your going to change your minimum pressure than put it at 9cm like Sleeprider hinted at.


RE: Why is my AHI worse the last few hours of sleep? - Apnea Infant - 03-30-2018

Strike a median between 8 and 9 if you like.

Your chart shows a lot of hypopnea & OSAs at pressures below 8-9.