IQs and Zs

Night owls are smarter than other people, and now we may know why. The modern world contains many features our slow-to-evolve brains still find unfamiliar—cars, TVs, hot dogs on a stick. But the world has always thrown new stuff at us, and brighter humans may adapt more ably.

Satoshi Kanazawa, a psychologist at The London School of Economics and Political Science, argues that, while we have specialized mental modules for navigation, social interaction, and other age-old tasks, is its own module handling only evolutionarily novel circumstances. And he has data showing that people with higher IQs are more likely to have values and preferences that just didn't make sense for our ancestors to embrace. One of those is staying up late.

A previous study found that evening people are smarter than morning people. In a new paper, Kanazawa replicates the finding and provides a theoretical grounding. Because the nocturnal lifestyle allowed by electricity didn't exist 10,000 years ago, we must now rely on general intelligence to override our early-to-bed instincts. So those with more of it stay up later. How much later? See below.

Night Lights

Bedtimes and wake-up times for Americans in their 20s by IQ.

Very Dull (IQ < 75)

Weekday: 11:41 P.M.-7:20 A.M.

Weekend: 12:35 A.M.-10:09 A.M.

Normal (90 < IQ < 110)

Weekday: 12:10 A.M.-7:32 A.M.

Weekend: 1:13 A.M.-10:14 A.M.

Very Bright (IQ > 125)

Weekday: 12:29 A.M.-7:52 A.M.

Weekend: 1:44 A.M.-11:07 A.M.