Preference for night or morning might be rooted in our genes

New research suggests that biological differences may account for why some people are "morning people" and others feel more energetic at night.

Emmanuel Mignot, MD, PhD, an associate professor of psychiatry at Stanford University, and colleagues at Stanford and the University of Wisconsin?Madison asked 410 adults when they like to sleep and work.

For example, they asked participants to describe their ideal sleeping schedule and the time of the day they feel most mentally alert.

They also drew participants? blood to look for differences in their "clock" gene?a gene that?s been tied to regulating circadian rhythms, or daily sleep?wake schedules.

The researchers found a link between two different forms of the gene and whether people were partial to morning or evening activity. Although most participants considered themselves brightest in the morning, about a quarter said they felt most awake during the late afternoon and evening. And nearly all of the "night owls" showed the same form of the clock gene.

While noting that this is the first study to find such a pattern, Mignot says it could mean our morning-oriented society treats night people somewhat unfairly.

Short of keeping the blinds open so that morning light wakes them up, there?s little night people can do to fight a genetic predisposition, he says. If further research confirms the pattern, he hopes employers take notice.

"The clever employer could use this sort of finding to adapt workers? schedules so that they?re more productive and happy," says Mignot, whose study is published in the September 15 issue of the journal Sleep (Vol. 21, No. 6, p. 568?576). "It also means some employees could be better than others at handling jet lag and shift work."

?B. Murray