Early Birds Have Different Brains Than Night Owls

If the early bird gets the worm, what does the night owl get? According to a recent study, "sleep disturbances, vulnerability to depression and higher consumption of nicotine and alcohol." The study is the first to hint at what brain differences might underlie a person's so-called chronotype---their natural tendencies toward sleeping and waking. Chronotypes fall into three categories---early, late or intermediate. About 10 percent of people have early chronotypes; 20 percent are naturally late risers, and the rest fall somewhere in the middle. But chronotypes indicate more than just when a person rolls out of bed. Studies have shown chronotype-related differences in hormones, lifestyles and brain functions between individuals. But are there differences in the brains themselves? To find out, researchers in Germany hooked up 16 early birds, 23 night owls and 20 middle-of-the-roaders to a diffusion MRI machine to see what was going on inside their heads. Turns out ...