City Life Causes Faster Circadian Rhythm In Birds, Study Shows

Study Shows Living In The City Speeds Up Biological Clock

Life in the city may not just be exciting, it might be speeding up your biological rhythm.

A new study has revealed that living in an urban environment speeds up the circadian rhythms of some animals.

The study, published Wednesday in the scientific journal Proceedings Of The Royal Society B, found that birds that live in cities start their day earlier and end it later. They also had faster -- but weaker -- circadian rhythms than blackbirds that lived in the forest. The study found that artificial light and noise associated with urban environments caused the quickening of the birds' circadian rhythms.

For a week, a group of scientists with the University of Glasgow in Scotland and the Max Planck Institute in Germany recorded the activity of a group of blackbirds living in the country and another group living in the city. They then recaptured the same birds and put them in a light- and sound-proof room, where a dim light was constantly on to prevent the birds from knowing what time of day it was.

After recording the birds' activity in the evenly-lit chamber for a week, scientists found that city birds were active for an average of 40 minutes longer per day than birds that had been captured in a rural area (about 30 miles south of Munich).

So can the same be said for humans?

Although the study's lead researcher Davide Dominoni told The Huffington Post that there hasn't yet been much study concerning whether people who live in cities may also have faster, weaker circadian rhythms, there is reason to believe city life affects humans as much (or more) than birds.

"There is already a huge body of research in the human biology field that shows that the Industrial Revolution with all its consequences has modified our 'body clock,'" Dominoni said in an email, pointing out that multiple studies have shown that women who work night shifts (like nurses) have a higher risk of breast cancer.

The University of Glasgow's Dr. Barbara Helm backed up Dominoni's statement. Speaking to the BBC, Helm said that previous research has shown "strong links" in humans between "disrupted sleep patterns" and "an increased incidence of depression and diseases including obesity and some types of cancers."

But don't get too alarmed. There's still no definitive proof that living in a city means you have a weaker circadian rhythm than someone living in rural Kansas. Just make sure to get enough sleep on a regular basis, and don't work a job that makes you work three or fewer night shifts per week.

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