Early Bird or Night Owl? Brain Scans Show They Differ

April 23, 2009


By Kate Stinchfield

THURSDAY, April 23, 2009 (Health.com) — If you’re an early bird, you know the afternoon slump all too well. By the time that 4:30 p.m. meeting rolls around, you’re fading fast. You may blame it on a big lunch or a dark conference room, but a new study suggests that a drop in daytime alertness may actually be hardwired in your brain.

What’s more, night owls—people who stay up later and feel more awake in the evening—may have a naturally occurring advantage over early birds, according to a study published Thursday in the journal Science.

It seems that your alertness depends on the balance of two factors: your natural circadian rhythm and the intensity of pressure to sleep. Sleep pressure progressively increases throughout the day, meaning that the longer you’ve been awake, the less alert you should be. Brain scans suggest that night owls may be less sensitive than early birds to rising sleep pressure.

“If we have found what can appear as an advantage for evening types, it’s that they are able to perform well after 10.5 hours spent awake, and that they’re able to outperform morning types,” says Philippe Peigneux, PhD, a professor of neuropsychology at the University Libre de Bruxelles in Belgium.

Next page: Caffeine to the rescue?

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