Curious about discrepancy in numbers

[snoozysue]

I had a "shocker of a night" last night.

My knees hurt, my back was sore and during the night I had a terrible cramp.
My AHI is almost always under 1.0. This morning my Dreamstation showed it to be 4.4

I had a look in Sleepyhead as I wanted to see if it was related to the cramp - which was what I suspected as I was in a lot of pain and moaning and groaning!
Sleepyhead showed hypopnea of 1.75 with no obstructive or clear airway obstructions.

Just curious as to why there is such a big difference in numbers - would welcome any insights
Thanks

[Sheriff Buford]

I get numbers all over the place at times.... but at the end of the month, I manage to be within my average. If I sleep real hard, my numbers tend to be higher.

Sheriff

[Pugsy]

Did you happen to have more than one sleep session last night? Meaning did you turn the machine off and the back on at sometime (or more than once) during the night?
If so that likely explains the difference in the reported AHI. Sometimes the on screen display only shows the most recent session and doesn't take into account the prior sessions.

[nicholasjh1]

I get numbers all over the place at times.... but at the end of the month, I manage to be within my average. If I sleep real hard, my numbers tend to be higher.

Sheriff

I would agree. IN fact along that note HIgher AHI sometimes means a more successful night as higher AHI can = went into a deeper sleep. If you numbers get too high from this deeper sleep it may mean you need a higher starting pressure.

Edit, Also as others have said, you can have clusters depending on how deep your sleep is, and you tend to sleep deepest when you first go to sleep, so it may be more likely to have a cluster of apnea's at the "start" of the night.

[snoozysue]

Did you happen to have more than one sleep session last night? Meaning did you turn the machine off and the back on at sometime (or more than once) during the night?
If so that likely explains the difference in the reported AHI. Sometimes the on screen display only shows the most recent session and doesn't take into account the prior sessions.

Yes I did, while I was having the cramp I turned off the machine for about 15 minutes.
Thanks for the suggestion - I was just curious and wanted to be sure I could trust the data on the display screen

Thanks

[Pugsy]

The data on the LCD screen was probably correct for the session it was reporting on ....only thing it didn't reflect the prior session before you turned the machine off for 15 minutes.
I am not sure just where the cut off is for starting a new session with a turn off in terms of minutes off. A brief turn off and back on for maybe a minute wouldn't be likely to start a new session. It has to do with how long the machine was off and I have never found just how long it would be before a new session is started.