Yale University researchers are on your mom’s side when it comes to fighting a cold: put on a sweater.

The immune system doesn’t combat cold viruses as well at lower temperatures, according to an early study in mice published last month in the Proceedings of the National Academy of Sciences.

Doctors have long understood that temperature affects the way cold viruses reproduce.

Akiko Iwasaki, a Yale professor of immunobiology who led the study, now has research to bolster the case for staying warm that she makes to her own kids.

“Fashion goes out the window when it comes to protecting my children,” Iwasaki said. “I bundle them up and they don’t like it. As a mother and as a scientist, it’s my duty to do that.”

The most common human illness, colds are the main reason that children miss school and adults miss work, according to the U.S. Centers for Disease Control and Prevention.

While colds generally run their course in seven to 10 days, they can sometimes lead to fatal asthma flare-ups and hospitalization of children with the chronic lung disease.