ORLANDO, Florida (Reuters) - An eight-week regimen of yoga proved safe for patients with chronic heart failure and helped reduce signs of inflammation often linked with death, according to a study released on Monday.

More than 5 million Americans have chronic heart failure, a long-term condition in which the heart no longer pumps blood efficiently to the body's other organs. Health problems and deaths from the disease remain high despite widespread use of effective drug and device therapies to treat the condition.

CHICAGO (Reuters) - A study of more than 5,000 youngsters in Switzerland has found those who smoked marijuana do as well or better in some areas as those who don't, researchers said on Monday.

But the same was not true for those who used both tobacco and marijuana, who tended to be heavier users of the drug, said the report from Dr. J.C. Suris and colleagues at the University of Lausanne.

WASHINGTON (Reuters) - Climate change could end globalization by 2040 as nations look inward to conserve scarce resources and conflicts flare when refugees flee rising seas and drought, national security experts warned on Monday.

Scarcity could dictate the terms of international relations, according to Leon Fuerth of George Washington University, one of the report's authors.

Global cooperation based on a resource-rich world could give way to a regime where vital commodities are scarce, Fuerth said at a forum to release "The Age of Consequences."

CHICAGO (Reuters) - Insufficient sleep can negatively affect preteens' metabolism as well as their exercise and eating habits, causing them to get fat, researchers reported on Monday.

Children aged 9 to 12 who slept less than nine hours a night were more likely to gain weight than their more rested peers, according to researchers at the University of Michigan's Center for Human Growth and Development.

A highly publicized series of wildfires has struck California in the last decade, putting a focus on homes in wildfire-prone areas and the flammable materials they are constructed from—including roofing, siding, and decking. Taking effect on January 1, 2008, the Wildland-Urban Interface Building Codes, developed by the California Office of the State Fire Marshal (SFM), aim to protect homes and the safety of occupants and firefighters. Among other provisions, the codes restrict relatively flammable decking, including wood-plastic composites.

The new codes affect “Fire Hazard Severity Zones,” identified by topography (fire spreads faster on slopes), vegetation that fuels fires, weather patterns, history of past wildfires, and likelihood of fire spreading from neighboring areas. Those zones affect a significant portion of the state, mostly in rural areas, but they also frequently intersect with populated areas. According to Kevin Reinertson at SFM, the standards have been projected to affect 8%–11% of new construction in California.

CHICAGO (Reuters) - An effort to map the genetic landscape of lung cancer has turned up a host of new genes, including one that controls the growth of cells essential for lung function, an international team of researchers said on Sunday.

This study of aberrations in the genetic code of lung adenocarcinoma -- the most common form of lung cancer -- found 57 changes frequently associated with the tumors.

Only about a third of the changes are linked with the 15 genes already known to play a role in lung cancer.

ORLANDO, Florida (Reuters) - More U.S. women are developing a type of artery disease that raises the risk of death from heart disease and stroke, researchers said on Sunday.

Researchers used U.S. government health surveys to track rates of peripheral artery disease, known as PAD, in people age 40 and up with no outward symptoms of cardiovascular illness. PAD is a circulatory condition in which narrowed arteries cut blood flow to the limbs.