Why is it that the only apnea episodes that awaken you are the ones that occur just as you’re falling asleep?
Is this caused by a collapsing airway that then becomes rigid and allows you to breathe once your brain arouses you that your oxygen levels have dipped?
Well, it’s certainly easy to draw that conclusion until you learn about a phenomenon called sleep-onset central apnea—also known as transitional central apnea.
There are actually different kinds of central sleep apnea. Put simply, CSA is when the body “forgets” to take a breath.
You can have the largest airway in the world, the biggest jaw and the most activated pharyngeal muscles during sleep…but still “forget” to take a breath.
So there you are, aware that you’re on the verge of drifting off to sleep, but right after this happens, you’re jarred awake by the awareness that you haven’t taken a breath for a while and feel very short of breath – leading to a big inhalation.
Or, the awareness can be described as being short on air, causing you to take that big deep breath, even hyperventilate a bit.
In fact, it’s common for people to overcorrect the problem with hyperventilation, which then sets them up for another arousal (the explanation for this is quite technical, and hence will not be given).
Then, all is well again and you gradually drift off towards the first stage of sleep…when suddenly, you’re again abruptly wakened by the need to take a breath.
And damn it, this keeps happening, sometimes delaying sleep for over an hour.
The big question: Does this keep happening after you finally fall asleep and become too deep in slumber to be jarred to conscious awareness of the need to breathe?
Or, does it cease once you’ve achieved the first stage of sleep?
Sleep Transition Apnea
STA, or sleep-onset (central) apnea, occurs in people who do not have obstructive sleep apnea and also in those who do.
The transitory pauses in breathing also occur in people who do not have the type of central sleep apnea that requires night-long PAP or oxygen therapy.
In fact, transitional apnea is a very common phenomenon of sleep onset, and quite frightening to those who fear that they’ll die if they don’t keep waking up to breathe again.
Many people eventually fall asleep within half an hour and, by definition, no longer experience sleep transition apnea at that point.
Plus, those who experience STA don’t always have it every night, and may, in fact, have it only occasionally.
For those who have it all the time and find it disturbing, supplemental oxygen is an effective treatment when there’s no obstructive apnea present.
Nevertheless, STA can have different causes including obstructive sleep apnea and period limb movement disorder.
But remember, it can also be present in people who are otherwise normal during the rest of their sleep and in these cases, is not related to upper airway resistance.
If transitional apnea describes your experiences, do not assume that this means you don’t have obstructive sleep apnea – especially if you have symptoms strongly suggestive of OSA:
• At least two trips a night to the toilet
• Partner witnesses gasps and paused breathing in the middle of the night
• Excessive daytime sleepiness
A sleep study will determine if, throughout the night, you are experiencing pauses in respiration and/or shallow breathing, and when and how frequently these events occur.
If the results of the study show that your only events are the sleep-onset pauses in breathing, and this phenomenon is fully explained to you in layman’s terms (the process is actually quite technical), this new knowledge may be enough to actually reduce these occurrences – as anxiety can contribute to bringing them on.