Gastro-esophageal reflux and laryngopharyngeal reflux disease are commonly seen in patients with obstructive sleep apnea. Many of you will have the typical throat clearing, post-nasal drip, chronic cough or hoarseness that's seen with laryngopharyngeal reflux disease. Sleep apnea causes your normal stomach juices to leak up into the throat, which not only causes you to wake up, but also causes swelling and inflammation in the throat.
We know that any form of breathing obstruction (apnea, hypopnea, RERA) can cause you to wake up. But what's not too commonly known is the fact that any degree of acid in the throat can stimulate certain chemical receptors, which causes you to wake up so you can swallow. It's thought that this is needed to prevent aspiration of stomach juices into your lungs.
A recent Japanese study not only confirmed these concepts, but found an interesting additional observation: While people with severe obstructive sleep apnea have mostly arousals due to breathing pauses, those with mild to moderate sleep apnea have a higher number of spontaneous arousals. Spontaneous arousals are noted on a sleep study when your brain waves go from deep sleep to light sleep or temporary awakening, without any objective evidence of breathing pauses.
What this study doesn't address is the fact that it's not only acid that comes up into the throat when you stop breathing. Your stomach juices also contain bile, digestive enzymes, and bacteria. An obstruction causes a tremendous vacuum effect that's created in the throat, literally suctioning up your normal stomach juices. This initial obstruction will lead to the typical respiratory arousal, but lingering juices will irritate the throat leading to spontaneous arousals. Think of your stomach juices as a sort of sensory form of stimulation, like a loud noise or a bright light. Your throat has a number of very sensitive chemical and pressure receptors that can cause your brain to wake up, without any physical obstruction.
There are also studies that show that chronic exposure to acid can make pressure sensors less sensitive over time, leading to longer and longer pauses with each obstruction.
Furthermore, there's research showing that some of these arousals don't ever show up on routine brain wave leads during a standard sleep study. This is because these protective reflex signals are so minimal that they stay in the deeper levels of the brain, never reaching the outer cortex.
I've always felt that spontaneous arousals are somehow related to breathing pauses. This study only confirms my suspicion that too many spontaneous arousals may be a sign of upper airway resistance syndrome or early obstructive sleep apnea.
What's your opinion on this? Do you have laryngopharyngeal reflux disease?