Elizabeth Kolbert reviews a couple of recent books on the science of sleep and hits on something that increasingly fascinates me, which is how different people have very different sleep patterns. One of those books discusses how those distinct patterns can put one quite out of step with normal society.
Till Roenneberg, the author of “Internal Time: Chronotypes, Social Jet Lag, and Why You’re So Tired” and a professor of medical psychology at the Ludwig Maximilian University of Munich, also blames the modern workday for our general drowsiness. But Roenneberg sees this not so much as a by-product of industrial capitalism as a quirk of human physiology.
Each of us has an internal clock, or, to use Roenneberg’s term, a “chronotype.” Either we’re inclined to go to bed early and wake up at dawn, in which case we’re “larks,” or we like to stay up late and get up later, which makes us “owls.” (One’s chronotype seems to be largely inherited, although Roenneberg notes, not altogether helpfully, that the “genetics are complex.”) During the week, everyone is expected to get to the office more or less at the same time—let’s say 9 a.m. This suits larks just fine. Owls know they ought to go to bed at a reasonable time, but they can’t—they’re owls. So they end up having to get up one, two, or, in extreme cases, three hours earlier than their internal clock would dictate. This is what Roenneberg refers to as “social jet lag”—each workday, owls fall asleep in one time zone and, in effect, wake up in another. By the time the week is over, they’re exhausted. They “fly back” to their internal time zone on weekends and sleep in on Saturday and Sunday. Then, on Monday, they start the process all over again.
For larks, the problem is reversed. Social life is arranged so that it’s hard to have one unless you stay out late on Friday and Saturday nights. But, even when larks have partied till 3 a.m., they can’t sleep in the following day—they’re larks. So they stagger through until Monday, when they can finally get some rest.
According to Roenneberg, age also has a big influence on chronotype. Toddlers tend to be larks, which is why they drive their parents crazy by getting up at sunrise. Teen-agers are owls, which is why high schools are filled with students who look (and act) like zombies. Roenneberg advocates scheduling high-school classes to begin later in the day, and he cites studies showing that schools that delay the start of first period see performance, motivation, and attendance all increase. (A school district in Minnesota that switched to a later schedule found that the average S.A.T. scores for the top ten per cent of the class rose by more than two hundred points, a result that the head of the College Board called “truly flabbergasting.”) But, Roenneberg notes, teachers and school administrators generally resist the change, preferring to believe that the problem is insoluble.
I’m an owl and I have always been one. I was that way before I was born, according to my mother, and remain that way today. I can force myself to fit into a normal work schedule, but if I don’t have to (and I no longer do), I will revert back to my normal pattern very quickly. When my job with the American Independent News Network ended in November, 2011, I was back to my normal pattern within a week (it probably helped that I was leaving for Vegas immediately after being told we were all being laid off).
With individuals having such differences, I don’t know how we can design things for both school and work that would allow each student or employee to follow the schedule that actually fits their chronotype. But I’m betting that if we did so, we’d see productivity in both spheres go up considerably. I am simply more productive at night. I write better and more clearly.