First Physical Evidence of Why You’re an Owl or a Lark
1st October 2013
Jessica Rosenberg at RWTH Aachen University in Germany and colleagues used diffusion tensor imaging to scan the brains of 16 larks, 23 night owls and 20 intermediate chronotypes. They found a reduction in the integrity of night owls’ white matter – brain tissue largely comprised of fatty insulating material that speeds up the transmission of nerve signals – in areas associated with depression.
“We think this could be caused by the fact that late chronotypes suffer from this permanent jet lag,” says Rosenberg, although she cautions that further studies are needed to confirm cause and effect.
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For example, research published last month suggests that night owls who cut their exposure to artificial light and boosted their exposure to sunlight found their body clocks shifted towards earlier waking and sleeping (Current Biology, DOI: 10.1016/j.cub.2013.06.039).