More sleep may keep arteries clearer

GIFT OF LIFE - Sinta, 11, gave birth to orangutan Natalia early Thursday morning at Taman Safari Zoo in Pasuruan, Indonesia. The word orangutan means ''man of the forest'' in the Malay language. A report by the Center for Orangutan Protection says because their habitat is being destroyed for palm oil plantations, only about 20,000 of the endangered primates remain in the Borneo Island jungle, down from 31,300 in 2004. (Sigit Pamungkas/REUTERS)

Lack of good night's sleep has been linked to risk factors for heart disease, including high blood pressure, high sugar levels, and obesity.

But the strength of the data has been questioned, in part because it's hard to reliably gauge how much shut-eye people get.

"That's a hard question to answer, because people probably overestimate the amount of sleep they get," says Diane Lauderdale, the principal investigator of a new study from the University of Chicago that examines sleep and heart disease.

To accurately measure sleep duration, researchers didn't rely on asking study participants to remember their sleep times. Instead, they fastened a motion sensor to their wrists, effectively capturing how long each person slept.

"Our study showed that middle-aged adults get a surprisingly short average sleep of only six hours," says Lauderdale. The research group then went on to find out how sleep duration affects the heart.

The researchers took pictures of nearly 500 participants' heart vessels using a CT scan and looked for calcifications - clumps of calcium that predict future risk of heart disease.

They found that people who slept an hour longer than other participants had a 33 percent lower chance of developing calcium deposits after five years - probably lowering their chances of developing future heart disease.
BOTTOM LINE: An hour more of sleep is associated with a decrease in coronary vessel calcification, even after controlling for factors such as high blood pressure and high cholesterol.
CAUTIONS: A single study linking sleep and calcification does not mean that poor sleep definitively leads to heart disease - more studies are needed to prove cause.
WHAT'S NEXT: Researchers still need to identify why less sleep may increase risk for heart disease - possible culprits may include cortisol, a stress hormone linked to heart disease, whose levels are affected by sleep duration.
WHERE TO FIND IT: Journal of the American Medical Association, Dec 24, 2008. SUSHRUT JANGI

Male birds nurturing their young with no help from their mates may be doing what their ancient dinosaur ancestors did. Dinosaur fossils found near nests of eggs show that millions of years before birds evolved, dinosaur fathers were sitting on large communal nests. David J. Varricchio of Montana State University and his colleagues concluded that the creatures were male for two reasons: Their body mass was larger than females', and their bones showed no signs of leaching the calcium and phosphorus needed to make the eggs that female Troodon, Oviraptor and Citpati dinosaurs laid. These three kinds of dinosaurs are already considered closely related to birds because of the hard-shelled eggs they laid, compared with parchment-thin eggs produced by lepidosaurs. The scientists speculate that these large, hard-shelled eggs required the mothers to concentrate on finding food and laying eggs while the fathers kept the nest warm. Among birds, males at least help hatch eggs and feed baby birds in 90 percent of species. Fathers nurture their young in fewer than 5 percent of mammalian species.
BOTTOM LINE: Birds' ancient relatives - the dinosaurs - set the standard for fathers nurturing their young.

CAUTIONS: Parental care patterns may be different in other kinds of dinosaurs than the three kinds whose fossils were studied.

WHAT'S NEXT: More research might reveal whether other bird behavior descended from certain dinosaurs.

WHERE TO FIND IT: Science, Dec. 19

ELIZABETH COONEY