Day five! Feeling a whole lot better today. I'm still not going to say 100%, but almost entirely back to normal. Not sleepy, not nauseous, not anything out of the ordinary. So M was correct: Not a flu. Hurrah!
Benefits thus far: I always sleep well, but sleeping just great. Nice and deep, rarely up. M, who doesn't always sleep well, is also sleeping well (for him), but he tends to go in cycles. I'm crossing my fingers this is a result of less salt in his diet. (He's not full Paleo, but by dint of living with me, is at least partly so.)
One other item of note worth, well, noting: Today's elliptical workout was really tough. There are some days you breeze through it and some you just feel like you've never been on the machine ever, and today was one of those days. Wonder what's up with that.