Time zones have outlived their usefulness. At least, a few academics seem to think so. Astrophysicist Richard Conn Henry and economist Steve Hanke argue that we should have just a single time zone for the entire world, all set to Greenwich Mean Time. Those of us in Washington, D.C. could still wake up at the same time relative to the sun — the clocks would just be flashing “2:00 a.m.” rather than “7:00 a.m.”


Oh look, it must be noon. (Mindaugas Kulbis/AP)

Tim Harford explored this question a few years back, comparing the U.S. multi-time-zone system with China’s single-zone approach. Basically, there’s a trade-off between coordination and sunlight. In the United States, people in each time zone get to experience sunrise and sunset at the same hour, more or less. That’s nice. The downside is that there are coordination problems — bankers in San Francisco have to get up at 5 a.m. to keep up with Wall Street, which means that everyone involved with the financial industry, including nearby coffee shops and so forth, has to get up at 5 a.m., leaving them out of sync with the rest of the city.

In China, meanwhile, everyone in the country is perfectly in synch with everyone else — people out east get up when people out west do — but some places suffer from screwy daylight patterns. Having been to Dunhuang, in western China, I can confirm it’s eerie when it’s still bright out at 10 o’clock at night. (China’s clock is set to Xi’an time, which would be the equivalent of putting the entire mainland United States on Central Time.)

So which system is preferable? Here’s one bit of evidence in favor of China’s approach: A 2008 study by Daniel Hamermesh, Caitlin Myers, and Mark Pocock found that our sleeping patterns are affected far more by our need to sync with other time zones than by when the sun rises and sets. The economists found that when daylight saving time pushes television schedules up or down in some states, lots of people will adjust their slumber habits accordingly. Meanwhile, shifts in actual daylight barely affect our long-term sleeping patterns at all.

That’s hardly conclusive, but it does suggest that we value coordination more than set sunlight patterns. So perhaps Henry and Hanke are onto something with their unified time zone proposals. Still, it sounds awfully disorienting.