This New Yorker essay on sleep explains why I have stopped sending emails at 3 a.m. so as to avoid comments that gently coerce me into sleeping like a normal person.
Wolf-Meyer refers to the practice of going to bed at around eleven o’clock at night and staying there until about seven in the morning as sleeping “in a consolidated fashion.” Nowadays, adults are expected to sleep in this manner; anything else—sleeping during the day, sleeping in bursts, waking up in the middle of the night—is taken to be unsound, even deviant. This didn’t use to be the case. Until a century and a half or so ago, Wolf-Meyer observes, “Americans, like other people around the world, used to sleep in an unconsolidated fashion, that is, in two or more periods throughout the day.” They went to bed not long after the sun went down. Four or five hours later, they woke from their “first sleep” and rattled around—praying, chatting, smoking, or making love. (Benjamin Franklin reportedly liked to spend this time reading naked in a chair.) Eventually, they went back to bed for their “second sleep.”
She (writer Elizabeth Kolbert) identifies two kinds of people, what researchers refer to as larks (early risers) and owls (late sleepers), both of whom suffer, in their own way, due to the overly uniform nature of our culture. One must get up too early to go to work, the other must stay up too late for a social life.
I used to say it was my goal to sleep only a quarter of my life (sleep is for the weak, I’ll sleep when I’m dead, etc etc etc), and maybe it’s killing me slowly (or not so slowly) to pursue this ambition. One experiment reported here was to keep rats awake days on end; after a couple weeks they keeled over. Tellingly, though, this experiment yielded little real insight into the mystery.
But Rechtschaffen and Bergmann could never figure out the precise cause of the rats’ deaths, and so, they wrote in a follow-up paper in 2002, even “that dramatic symptom did not tell us much about why sleep was necessary.” Rechtschaffen has observed that “if sleep doesn’t serve an absolutely vital function, it is the greatest mistake evolution ever made.”