The study found that fevers didn't last as long in winter daylight conditions, the hamsters resumed normal eating patterns sooner after infection, and cytokine production - one measure of immune function - was reduced.

The researchers believe that illness symptoms are reduced in winter so the animals can save energy to survive during a season when food is scarce and conditions are harsh.

"Some of the body's defenses against infection, such as fever, take a lot of energy," said Randy Nelson, co-author of the study and a professor of psychology and neuroscience at Ohio State University.

"If animals have to maintain a fever for too long during the winter, it is going to strain their ability to survive."

The changes in symptom response are tied to the changing length of daylight from summer to winter, said Staci Bilbo, a doctoral student in psychology at The Johns Hopkins University, currently working in Nelson's lab. "Siberian hamsters respond to day length to orchestrate their response to infections," she said.

Bilbo and Nelson conducted the study with Ning Quan, assistant
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Contact: Randy Nelson
Rnelson@osu.edu
614-538-9526
Ohio State University
25-Feb-2002