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Every day, people are exposed to hours of artificial light from computers, office lights, even 24-hour lighting in hospitals. 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 normal conditions – 12 hours of light, followed by 12 hours of dark.
During the study, reported in Current Biology, 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. While earlier research found excessive light exposure may affect cognition, the new research showed a surprising effect on muscles and bones.
“Not only did motor performance go down on tests, but the muscles themselves just atrophied, and mice physically became weaker after just two months,” said Chris Colwell, a sleep specialist at the University of California at Los Angeles, who was not involved with the study.
The good news is the effects of light exposure appear to be reversible. When the study rats returned to their natural light-dark cycle, their health returned to normal after two weeks.
Researchers are planning a human challenge study – this winter, when mosquitoes aren’t biting – to help speed development of much-needed Zika vaccines, and they need volunteers.
A human challenge study is when healthy – and nonpregnant – people agree to be injected deliberately with a virus, and allow scientists to track how their bodies react.
If government regulators agree to the study, researchers could begin injecting paid volunteers with different amounts of lab-grown Zika virus as early as December. That information will help the researchers later, when they’re ready to test an experimental Zika vaccine.
“We can look at things that you just can’t do in someone who’s naturally infected,” said Dr. Anna Durbin of Johns Hopkins Bloomberg School of Public Health, who is leading the work.