Cities ‘alter body clocks’

City living alters our daily body clock, making us active for longer and less rested, a study suggests.

Researchers compared the internal rhythms of blackbirds living in the countryside and in urban areas and found they differ significantly.

The city birds began their days earlier and ended them later, being active for around 40 minutes longer than the rural blackbirds.

Internal clocks of the city-dwelling birds were “less robust” and more prone to disturbance, the researchers said.

The differences in urban birds may have developed in response to artificial light and increased noise, they said.

The study team captured adult male blackbirds from Munich and from a nearby rural forest. They fitted each one with a lightweight radio-transmitter which monitored their daily activity in the wild for 10 days before the birds were recaptured.

They were then kept in light-proofed, sound-insulated chambers and their rhythms measured without any environmental information that could serve as a “clock”. Once the tests were complete, the birds were freed.

The research, a collaboration between Glasgow University and the Max Planck Institute for Ornithology in Germany, is published in the journal Proceedings Of The Royal Society B.