Well this morning I had a classic example of SWJ show up in my data. My alarm went off right around 7:30 AM and I woke up to turn the alarm off. I didn't turn the cpap off because I wanted to get a bit more sleep. Even before looking at the data I knew that it took me about 10-15 minutes to get back to "sleep" and I also knew that I didn't sleep very long before throwing in the towel and getting up a few minutes before 8:00AM.
This is what the flow rate looks like for the period between 7:28 and 7:54:
As you can see---just before the wake around 7:30, my breathing is nice, steady sleep breathing. The very large breaths around 7:30 are when the alarm went off and I woke up enough to turn it off. And then you'll notice that my breathing gets very irregular and all kinds of events are being scored. The last OA is scored around 7:42 and I suspect I actually did drift off into Stage 1 sleep for the last 12 minutes before waking up and deciding to just get up for the day.
This mixture of OAs, Hs, CAs, and snoring is pretty typical of my SWJ breathing. I catch myself "snoring" a lot when I start to get very relaxed, but when I'm still awake---particularly if I'm lying on my back like in a yoga class during savasana relaxation/meditation. I suspect that the reason my SWJ apneas are as likely to be scored as OAs as they are to be scored CAs may have to do with my epiglottis---that's the bit of tissue that closes off your windpipe when you swallow. I suspect that I have a tendency to "close" my epiglottis when I hold my breath AND I also am aware that I do tend to do a lot of swallowing when I'm dozing or super relaxed. So I strongly suspect that if my epiglottis is closed over my windpipe when I stop breathing just long enough for an apnea to be scored during SWJ, the PP data makes it look like the apnea is an OA one instead of a CA one.
If we take a closer look at the beginning of the cluster of SWJ breathing, it looks like this:
This shot shows the clear shape of my normal sleep breathing inhalations to the left of the wake at 7:30. You can see that the H scored at 7:31 is very short in duration; it's most likely a pause in breathing caused by the slight hyperventilation at the wake itself. The OA at 7:32 and the H at 7:33 might be sleep transitional---there's a tiny bit of evidence of the beginning of a normal sleep breathing pattern just before these events, but I clearly don't make it all the way to sleep. I was dozing at this point and trying to decide if I wanted to just get up or not. So the idea that I might slip momentarily into Stage 1 sleep and then back to wake is not farfetched. After the two snores, there's another "almost" apnea at a bit after 7:34:30. This only lasts 7-9 seconds when I zoom in on to the point where you can easily see the length of each breath. And if I zoom in that far, it's even clearer that this is sleep transitional breathing---my sleep transition breathing pattern is trying to establish itself as I try to go back to sleep, but again I wake back up because my mind is already focusing the fact that I don't really know if I want to go back to sleep or not. Same thing is true for the last two OAs in this shot. If you look carefully, you can see the mixture of sleep breathing and non-sleep breathing right around both sides of these events.
So that's what SWJ breathing looks like in my data. The fact that I know that I was dozing is just the icing on the cake here: This is clearly SWJ breathing and the fact that this last 25 minutes of data has 7 events in it doesn't really mean anything---chances are that NONE of those events are "real" in the sense of being scored on an in-lab PSG.