Turns out I'm not alone. People using CPAP machines are prone to ear infections.
Sleep apnea, for those who don't know, is a breathing problem that affects people when they sleep. Tissues in your throat close off, airways in your nose are too narrow, and you end up having interruptions in the flow of oxygen that occur repeatedly through the night. Snoring -- loudly, and at times gaspingly - is one sign. Night sweats, waking up frequently to go to the bathroom, and daytime fatigue are other common symptoms. If I recall, men tend to suffer from apnea more than women; and the likelihood of developing apnea is higher in men in their mid-to-late 30's, getting worse as you age. Being overweight - which I am - also increases the risk. In very severe cases, people can die from sleep apnea.
I was diagnosed with "severe obstructive sleep apnea" about five years ago. Surgery -- cutting out part of your soft palate, uvula, tonsils, and etc. -- is sometimes recommended (see picture, below, which I took of a friend's throat four days after her surgery); but the most common and effective form of treatment is something called a CPAP machine. One wears a mask over the nose, hooked up to a machine which blows air - just ordinary air - into your nasal passages. The continuous pressure of the air keeps your nose and throat open, so you can breathe when you sleep; you don't snore, don't gasp, and wake up much more refreshed and alert. It takes a little while to get used to the mask, but once you do, your CPAP machine becomes a close friend.
Using a CPAP machine has side effects, though, which nobody told me about: in particular, the constant air pressure can affect your middle-ear. Whether it's just the pressure, or if bacteria and such are getting blown around inside my head when I sleep, I don't know, but I've had about four or five ear infections in my left ear - the side I breathe best through - since I started using the machine. (Like most people, I've barely had ear infections otherwise in my adult life). And either these, or changes brought about because of the pressure inside my head, have led to a gradual loss of hearing in my left ear. It's gotten worse over the last couple of years, so that I would guess that my hearing in my left ear is now 40% or lower; I've had to start retraining myself to talk on the phone with my right hand and ear, since when I try to talk on my left side - my preferred ear, for phone conversations - I have trouble hearing them. I have to try to remember to sit with my friends to the right at movie theatres, in case they want to whisper something to me. Whispering in my left ear means I won't be able to understand what you say, period.
Since I love music, and since I need to be able to hear my students' English as part of my job, the prospect of further hearing loss in my left ear scares the hell out of me. The idea of surgery is also pretty distasteful; I'm partial to my uvula, in particular (and am not sure the surgery really works). Looks like it's time to lose some weight and to start with some serious breathwork. I don't much want to choke to death in my sleep, but I don't want to go deaf, either.