Several friends have told me that it sounds like I have sleep apnea. I wondered about that when this first started happening, and I poked around on a few web sites, but I couldn't find a good description of what it's supposed to feel like, so I wasn't sure. Now that I really think about it though, I'm pretty sure that's what this is. At any rate, unless I run across a sliding-scale sleep disorder clinic in Austin, I don't know what I can do about it. It's not exactly an emergency, even though it sure feels like one for a few seconds in the middle of the night. Sleeping on your side is advised, and that seemed to work last night anyway.
One thing I found interesting in my research is that memory problems and sleepiness are always listed among the symptoms of sleep apnea. I've had difficulty waking up ever since I can remember, I have almost always my whole life been sleepy during the day, and my memory is notoriously unreliable. I've never really been able to retain information for very long. Maybe I've had sleep apnea all my life, and I'm not actually dumb and lazy (to use the lexicon of my family). It's very satisfying to have a medical excuse.