Every day, people are exposed to hours of artificial light. Now new research in animals shows that excessive exposure to "light pollution" may be worse for you than previously known, taking a toll on muscles and bones. Researchers at Leiden University Medical Center in the Netherlands tracked the health of rats exposed to six months of continuous light compared with a control group of rats living under 12 hours of light, followed by 12 hours of dark. The rats exposed to continuous light had less muscle strength and showed signs of early-stage osteoporosis. They also got fatter, and some markers of immune system health worsened. The good news is the effects appear to be reversible.

Arthritis drug may help Alzheimer's risk

A drug used to treat rheumatoid arthritis may have benefits against Alzheimer's disease, researchers report. Rheumatoid arthritis is an autoimmune disease believed to be driven in part by tumor necrosis factor, or TNF, a protein that promotes inflammation. Drugs that block TNF, including an injectable drug called etanercept, have been used to treat rheumatoid arthritis for many years. TNF is also elevated in the cerebrospinal fluid of Alzheimer's patients. In people older than 65, the prevalence of Alzheimer's disease was more than twice as high in people with rheumatoid arthritis as in those without it. But unlike patients treated with five other rheumatoid arthritis drugs, those who had been treated with etanercept showed a significantly reduced risk for Alzheimer's disease. Still, the lead author, Dr. Richard C. Chou of Dartmouth, said that it is too early to think of using etanercept as a treatment for Alzheimer's.