Larks and owls

This New Yorker article about sleep is pretty interesting. Short version: we don't know much about sleep except that most people don't get enough. 

The article defines "larks," people who like to go to bed early and cannot sleep in very late, and "owls," those who have trouble falling asleep early and like to get up late.

And this affects their lives quite a bit:

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.