Erwin Schrödinger, the Nobel-prize-winning Austrian physicist, was able to make major contributions to the fields of quantum mechanics, general relativity, and color theory during his lifetime. There was only one caveat: He was not able to make those contributions ... in the morning.

“He couldn’t work in the mornings at all,” his wife, AnneMarie, said in an interview. “The [Max] Planck lectures—as you know, it was 30 or 40 years ago that Planck was in Berlin—were given in the morning from nine to ten. When he got this very, very honorable call to Berlin, he wrote first thing and said, ‘I’m very sorry, but I can’t keep the lecture hours because I can’t work in the morning.’ ... They understood, and changed it to the afternoon—two lectures, one after the other—on two days.”

Ah, to be so famous that a major university rearranges its events just so you can hit the snooze button.

Scientists would later classify people like Schrödinger as “owls”—people who prefer to wake up late and are more alert in the evenings. It’s one of two basic chronotypes, or preferred sleep schedules. The other is “larks,” or crazy people those who prefer early mornings.

But now, scientists in Russia are proposing that there are actually four chronotypes: In addition to early and late risers, they say, there are also people who feel energetic in both the mornings and evenings, as well as people who feel lethargic all day.