Central events during sleep onset are very common, even in people without sleep apnea. It happens because our O2/CO2 balance needs change as we go from one stage of sleep to another. If we think of the O2/CO2 balance needs as a speed limit on highway, I'm sure we have all been guilty of not dropping our speed as quickly as we should when the speed limit changes from 55mph to 35mph (unless there happens to be a cop sitting right by the sign
). When we see the new speed limit, we often just take our foot off the gas, coasting to lower speed; but sometimes we have to gently brake to bring our speed in line with the posted speed and sometimes the new speed limit sneaks up on us suddenly and we end having to slam on brakes to correct our speed. A sleep onset central is sort of like that- our body is trying to coast from one need level of O2/CO2 to another, and sometimes that means we're not going to breath for several seconds, maybe even more then 10 seconds, until we're 'going the correct speed limit'. But if you panic and think something is wrong because you are not breathing, its like you stomp on the breaks- which not only terminates the apnea event, but also fully wakes you back up. Have you ever been heavy traffic and everyone is slowing down at about the same rate in unison? And what happens if one person panics & slams on their brakes? It throws everything out of wack, the comfortable rhythm & unison all the drivers were experiencing is gone, replaced by chaos.
For the majority of people, like 99+ out of 100, the only concern/problem/issue with sleep onset centrals is any anxiety the person may attribute to them. The sleep on central itself is not stressful on your body anymore then if you hold your breath while walking near an obnoxious odor. Now if a person panics or feels overly anxious when they notice a sleep onset central central, that anxiety can be stressful on the body, making it difficult to fall asleep, as some of you have noticed. And of course once you start feeling anxious & panicky, it only makes the situation worse, as then you're hypervigilant, waiting for the next indication of a sleep onset central event to stomp on the brakes, waking yourself up out of Stage I sleep. Your sleep onset has become like the chaos on the highway from one person slamming on their brakes. The trick is how to keep your sleep flowing & not being the one to slam on the brakes
I happen to be that 1 out of 100 that experiences significant sleep onset centrals, though for the most part, I just sleep through them. My central events are not limited to sleep onset either, I have Central Sleep Apnea, with an AHI of 60+, which has only recently been able to be fairly well controlled since I switched to the new VPAP Adapt SV from the best available treatment of the time, BiPAP ST. Last fall I had to do another split night sleep study, which was one of the few times I had tried to sleep with BiPAP ST in over 3 years. During the 2 hours without BiPAP ST, I spent over an hour having sleep onset centrals that were so bad they couldn't even score them as apneas because they were happening so rapidly and the sleep between most could only be described as 'microsleeps'. Never once did I panic- central apneas & periodic breathing are normal for me, thought at that level, they are far from normal 'normal'. I knew I was having more problems falling asleep and staying asleep, and that it was due to central events, but the reason I knew it was because my history, not because I was acutely aware of each centrals happening. I could feel my breathing rate slowing down as I drifted off to sleep like it normally did when I used my BiPAP ST, but that was it. I honestly thought I was asleep most of the time, and only woke to the point of being aware I was awake once or twice. Once I did get into Stage II and deeper stages of sleep, I continued to have central events & periodic breathing consistently throughout the sleep study, both without & with BiPAP ST. Even with the VPAP Adapt SV, I still have sleep onset centrals, though they are not nearly as bad as I experienced during the non-treatment portion of that sleep study.
When it comes to sleep onset centrals, if you've had a sleep study that has ruled out CSA as a problem, then it is one of those times when you really need to listen to your doctor when he tells you not to worry
about them. Alone, the central events are not harmful, but overreacting to them can be. Central sleep apneas are a normal part of variability in our breathing while we sleep- having some central apneas doesn't mean you have CSA; you have to have a certain number per hour, which excludes those centrals events which are perfectly normal. If you've been diagnosed as having OSA and been prescribed a CPAP, you really need to work with your doctor & DME to make it work for you- as frightening as a few onset central can seem, its nothing compared to the battle your body undergoes as you struggle to breath against an obstruction while you sleep.