May 14, 2008

Sloths Get a Bad Rap for Being Lazy

New research suggests that the sloth, the funny looking tree-dwellers that are commonly known as lazy creatures that sleep all day, may not be as lazy as we thought.

Sloths in captivity often sleep for more than 16 hours a day, but sloths in the wild get less than 10 hours.

Scientists looked at sloths living in the rainforest of Panama and tagged them with sleep monitoring devices.

These new findings could help researchers discover more about sleep disorders in humans.

This study demonstrated for the first time that it was possible to record sleep in a wild animal, according to Lead researcher Niels Rattenborg, of the Max Planck Institute for Ornithology in Starnberg, Germany.

"The real exciting finding was that they only slept 9.6 hours a day, which is much less than what people popularly believed and less than had been observed in a previous study of sloths in captivity," he said.

"So they still may be sloth-like in terms of their speed of movement but in terms of their sleep they don't seem to sleep an inordinate amount of time."

Dr. Rattenborg said the study attempts to find traits that predict whether an animal sleeps more or less than another species"”knowledge that could provide clues to the function of sleep.

"I think this finding is really going to open the door to a whole new age of sleep research on animals sleeping in their natural habitat," Rattenborg said.

Different animals require different amounts of sleep. A giraffe can survive on just 2 hours a day, while a python will sleep for more than eighteen hours.

Scientists from Germany, Switzerland and the US developed a small machine capable of monitoring brain patterns associated with sleep. They used these machines to study sleeping patterns in wild sloths.

Three female brown-throated three-toed sloths were caught from the rainforest near the Smithsonian Tropical Research Institute on Barro Colorado Island, Panama.

The creatures were released back into the wild after being fitted with the data recorders.

Several days later the sloths were re-captured and measurements showed that they slept for an average of 9.6 hours a day, compared with a sleep time of 16 hours a day reported in sloths kept in captivity.

"Animals tended to sleep much more in captivity, where they have all their needs met," said Dr. Neil Stanley, an expert in sleep disorders at the Norfolk and Norwich University Hospital, UK.

"It's intuitive that animals would sleep less in the wild than in captivity"”this technology gives us the opportunity to prove that's true," he said.

Many unresolved questions linger despite years of research into the function of sleep.

It is understood that sleep plays an important role in maintaining normal mental functions, but the precise mechanisms are unclear.

The study's findings were published in a Royal Society journal.


On the Net:

Max Planck Institute for Ornithology

Smithsonian Tropical Research Institute