has shown that
long-term, chronic stress can
suppress the immune system.
This short-term enhancement is
stronger during winter than
during summer.
Staci Bilbo, a doctoral student
in psychology at The Johns
Hopkins University, was the other lead author on the study. Bilbo
is currently working in the lab of Randy Nelson, another
co-author and professor of psychology and neuroscience at Ohio
State.
The study involved 50 Siberian hamsters. Using artificial light, the
researchers exposed half of them to long days (15 hours of light
per day) to simulate summer conditions. The other half lived in
short days (9 hours of light per day) to simulate winter
conditions.
After 10 weeks of living under these conditions, some hamsters
were tested for levels of key immune cells in their bloodstream,
including leukocytes, lymphocytes, T cells and NK cells.
The results showed that hamsters living in winter-like conditions
have higher baseline levels of these immune cells than do
hamsters living in summer-like daylight conditions.
"It is more difficult for hamsters to survive in the winter because
of stressors like cold and reduced availability of food," Bilbo
said. "We found that the animals seem to use the length of day to
warn of the onset of these stressors and then to enhance their
immune system when winter approaches."
'"/>
Contact: Firdaus Dhabhar
Dhabhar.1@osu.edu
614-688-8562
Ohio State University
18-Mar-2002
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