I've been adjusting my sleeping habits.
Like most of us, I grew up believing that one must get eight hours of sleep a night and that those hours had to be in a continuous chunk. The latter was rarely if ever explicitly stated; it was just assumed. Eight hours is eight hours straight.
So, when I found myself nodding off at 8, 8:30, or 9 PM I'd set myself some task that would keep me awake at least until 9:30 or 10. And when I'd waken in the middle of the night I just lay there in bed until I went back to sleep. Sometimes that happened quickly and sometimes it didn't.
And I'd take frequent naps during the day.
Then I read David Randall's article in the NYTimes. Shazaam! You mean it doesn't have to be eight continuous hours? You mean this 8-hours thing is a recent invention, that people routinely awaken in the middle of night and do stuff? That there was a lot of napping in the world, I already knew that, and did it myself. But the other stuff? Hot-diggity-dawg!
Now when I feel sleepy at 8PM I go to bed. And when I awaken at midnight or 1PM or 2PM or whenever, I'll get up and work for an hour or two. No problems.
And the napping continues.