I can remember a time when sleep lasted eight hours, when nighttime was a clear barrier between one day and the next. But for many years now I can count on patchwork sleep at least a couple nights a week.

Sometimes I pop up, ready for the day — only the day is still night. I take full responsibility for this restiveness and have all sorts of strategies (occasionally successful) to counteract it.

But other times I wake up due to — ahem — environmental factors — the primary of which is having a teenager in the house. This teenager may not go to bed until 2 a.m. if she has a lot of homework. And sometimes she gets hungry after midnight so she cooks. During the summer, when we have two or three daughters at home the shower is as likely to be running at midnight as it is at noon.

In other words, for the last few years our house has come to resemble a 24-hour hotel, a full-service establishment with round-the-clock service. I love our house, I love our kids. But I’m exhausted.