Gerbils also get the winter blues

Dec 20, 2010 By Katharine Gammon
A species of gerbil can get a bit moody when it doesn't get enough sunlight. Credit: American Friends of Tel Aviv University

December 21 -- the date of the winter solstice -- marks the shortest day of the year. Many people may find themselves wanting to spend more time on the couch and less time with friends -- one of the effects of seasonal affective disorder.

Zoologist Noga Kronfeld-Schor of Tel Aviv University in Israel thinks that studying mood disorders in animals -- specifically, wild gerbils -- may yield new clues about the way , or SAD, works.

Kronfeld-Schor and her colleagues took a group of fat sand rats -- actually a type of gerbil -- from the a research zoo in Tel Aviv and kept them in a room where they received only about five hours a day of light for three weeks, instead of the usual 12. The gerbils began to respond to the effects of less light.

"No, the rats don't lie down on the couch," said Haim Einat of the University of Minnesota Duluth, who also worked on the study. "But there are some behavioral aspects to depression."

The gerbils behaved strangely: they mated less, turned down tempting sugar water (usually ambrosia for rodents), acted more submissively and explored their surroundings less often. The scientists also noticed that the animals gave up more quickly trying to swim out of a cylinder partially filled with water and no way to escape.

Previous studies examined depression in mice and rats, naturally nocturnal animals. This research marks the first time scientists have studied seasonal disorders in animals that are active during the day.

After triggering blues in the rodents, the researchers then tested some of the available treatments for SAD. Depressed blasted with an hour of bright light each morning quickly regained their normal socializing behaviors. The researchers also tested a common anti-depressant, which helped the animals, but not as much as the morning light.

"The results with light were even better than any drug we used before," said Kronfeld-Schor, in research to be published in the journal Neuropsychobiology in early 2011. "And in humans it's been observed that light treatment in the morning works better than in the evening."

But what about animals in the wild that experience only a few hours of light per day during the winter? Can polar bears feel down? Kronfeld-Schor said that while it may not be exactly depression, there's an evolutionary reason for slowing down in the winter.

"If food availability decreases during winter, and mating success decreases during winter, and it's dangerous to be outside because of the temperature, then it makes sense to decrease activity level," Kronfeld-Schor said.

"It's difficult to tell if animals get depressed," said Randy Nelson, a professor at Ohio State University who has studied depressive-like behavior in Siberian hamsters.

He said that reduce their behavior in winter to focus on survival, and that humans were no different in our evolutionary history.

But while slothful behavior may have kept early humans ancestors alive, blaming evolution still isn't a great excuse for missing a holiday party.

Explore further: Sex? It all started 385 million years ago (w/ Video)

Provided by Inside Science News Service

5 /5 (2 votes)

Related Stories

Fat sand rats are SAD like us

Nov 08, 2010

(PhysOrg.com) -- Saying goodbye to summer can be difficult for everybody. In some people the onset of winter triggers Seasonal Affective Disorder, or SAD, a mood disorder in which sufferers experience symptoms ...

Seasonal depression may affect hamsters

Nov 16, 2005

An Ohio State University study suggests hamsters may suffer from symptoms of anxiety and depression during the dark days of winter, just as some humans.

Networking around the clock

Apr 05, 2007

A Brandeis University study published in Cell this week shows for the first time experimentally that the circadian cells in fruit flies function as a network that enables the insects to adapt their behavior according to sea ...

Recommended for you

'Red effect' sparks interest in female monkeys

Oct 17, 2014

Recent studies showed that the color red tends increase our attraction toward others, feelings of jealousy, and even reaction times. Now, new research shows that female monkeys also respond to the color red, ...

Roads negatively affect frogs and toads, study finds

Oct 17, 2014

The development of roads has a significant negative and pervasive effect on frog and toad populations, according to a new study conducted by a team of researchers that included undergraduate students and ...

All in a flap: Seychelles fears foreign bird invader

Oct 17, 2014

It was just a feather: but in the tropical paradise of the Seychelles, the discovery of parakeet plumage has put environmentalists in a flutter, with a foreign invading bird threatening the national parrot.

Amphibians being wiped out by emerging viruses

Oct 16, 2014

Scientists tracing the real-time impact of viruses in the wild have found that entire amphibian communities are being killed off by closely related viruses introduced to mountainous areas of northern Spain.

User comments : 0