STEVE INSKEEP, HOST:
OK. For those who are morning people, listening to MORNING EDITION is no challenge. But for night people, paying attention right about now might be difficult. NPR's science correspondent Joe Palca reports there may be a health benefit from being a morning person as opposed to a night owl.
JOE PALCA, BYLINE: For an evening person, nothing's more annoying than a morning person. But we can't help it.
JACQUELINE LANE: Everybody has an internal body clock.
PALCA: Jacqueline Lane is a geneticist at Massachusetts General Hospital. She says your internal clock determines something called your chronotype.
LANE: What chronotype is is there are some individuals whose internal body clock runs a little bit more towards the morning and some whose runs a little bit more towards the evening.
PALCA: Lane says studies in the past have pointed to some health risks of being an evening person.
LANE: They've shown that there's an increased risk of different psychiatric disorders with being an evening person as well as some metabolic conditions like obesity and diabetes. But the question has always been, is that driven by the environment?
PALCA: In other words, where people live, what they eat how, much exercise they get.
LANE: Or is that driven by an underlying biology that we might have as a morning or an evening person?
PALCA: That is, how big a role do your genes play? So she and some colleagues in Europe turned to something called the UK Biobank for answers.
MICHAEL WEEDON: So the UK Biobank is an amazing study of 500,000 people from the U.K. with just an enormous amount of data available on them. And it's all publicly available data.
PALCA: Michael Weedon is a geneticist at the University of Exeter Medical School. Some of the data in the Biobank comes from questionnaires. What's your diet like? How much exercise do you get? What are your sleep habits like? But there's also a crucial piece of biological information about people stored in the bank.
WEEDON: Everyone in the UK Biobank had DNA taken.
PALCA: So Weedon and his colleagues examined the DNA of people who described themselves as morning people and compared it with the DNA of those who described themselves as evening people, looking for differences. As they report in the journal Nature Communications, Weedon says they found some. For example, there were differences in the genes known to be involved in controlling the internal body clock. You'd expect that. They also saw differences in genes involved in the development of the part of the eye known as the retina.
WEEDON: Which kind of makes sense because light is one of the things that resets the circadian clock.
PALCA: The circadian clock is that internal body clock. More surprising was what they didn't find.
WEEDON: So it doesn't appear from the data we've got so far that being a morning or an evening person influences risk of obesity or Type 2 diabetes.
PALCA: It did, however, appear that being a morning person was associated with better mental health. As a morning person, I'm encouraged by that. Joe Palca, NPR News.
(SOUNDBITE OF DEBBIE REYNOLDS, GENE KELLY AND DONALD O'CONNOR SONG, "GOOD MORNING") Transcript provided by NPR, Copyright NPR.