How Our Circadian Rhythms Have Learned to Ignore Time Zones

Illustration for article titled How Our Circadian Rhythms Have Learned to Ignore Time Zones

Right around this time every year, the world starts to make sense. It gets darker earlier and I get tired earlier, which means I get a better night of sleep. It turns out that I'm not just imagining things. When we go to bed is still determined by that impending darkness, even if our time zone tells us something different.


Jawbone has been releasing some interesting data lately culled from its fitness trackers, like demonstrating when August's Napa earthquake shook Bay Area people awake. In an awesome new map (which you can interact with on their site), we can see when America goes to sleep. And what's most fascinating here is how much our exposure to daylight still dictates when we hit the sack—even when the clock says it's "bedtime."

Illustration for article titled How Our Circadian Rhythms Have Learned to Ignore Time Zones

Even without the time zones drawn in here, it would be very, very easy to tell where they are, just based on when people go to bed. On the eastern sides of each time zone, people go to bed earlier, and on the western sides, they go to bed later. (The one anomaly is Vegas, because Vegas.)

Why? Jawbone explains it well:

  1. Imagine two people in Kentucky, very close to each other but on opposites sides of the time zone border. If they both go to bed 4 hours after the sun goes down, their clocks will say that the person in Eastern Time went to bed one hour later than the person in Central Time.
  2. Now let's look at the Central Time Zone. It's 6pm, and the sun has gone down in the middle of Kentucky. It's also 6pm in western Kansas, almost 1000 miles away, but the sun will not go down for another hour. So people go to bed later in the western edge of the timezone than the eastern edge.

Maybe if you wanted to get more sleep in general, you might consider moving to the far eastern edge of a time zone, as it would get darker "earlier" and your rhythms would start to shut your body down earlier. I say maybe only because what Jawbone doesn't show is how the same patterns might influence when we wake up. But I'd say when we wake up is more determined by schedule—it's more likely that you'll have a set time you need to get up, whether or not the sun is already rising.

It's pretty amazing that even with all these technological cues, our bodies are still smart enough to know when to go to sleep, despite our time zones trying to mess with our heads. Of course, in a few weeks, we hit Daylight Savings, which throws everything off. [Jawbone via Fast Company]




As a full-time working adult, I actually returned to my childhood bedtime. 9:30 PM and I am in bed. Of course, I am a morning person, so I'm up between 5:00-6:00.

Apparently I'm the outlier in this data set