I haven't slept. I have a concussion.

No, seriously. I can't sit up for very long before the floor tilts and my stomach lurches and my head swims and I have to crawl back to my bed.

I got the concussion in kickboxing class on Thursday night. I'll get back to that when the room stops turning. The short version is that I landed chest-first (cut it out, I heard that) on a hardwood floor and the impact traveled right up my spine to my head. Check it out: I didn't even directly whack my head. But the result was pretty much the same. I got my bell rung.

And, obstinate and oblivious as I am, I jumped right back to my feet and went on with the class. By the time I got home an hour and a half later, I had mostly forgotten the crash. I was high on endorphins and chalked up my light-headedness to the workout. I had some trouble lifting my arms in the shower and chalked that up to the workout, too, along with the waves of drowsiness which followed.

When I bolted out of bed less than an hour later to be violently, pyrotechnically ill, I didn't know what to think. We have touchy stomachs in my family. So I had an answer there too. And in any case, I was too sick to think about it much.

I didn't sleep much. Fitful doze, up for water, check e-mail, get dizzy, lie down, fitful doze. Lather, rinse, repeat. It was Tony who suggested I'd probably sloshed my brain around when I hit the floor. I checked the symptoms of concussion at WebMD and there I was. Nausea: check. Headache: check. Difficulty concentrating: check. Weakness: check. And so on, ad nauseum, so to speak.

I'll be fine in a day or so. But now I'm going back to bed.