Sloths Aren't So Slothful After All -- Youngsteadt 2008 (514): 2 -- ScienceNOW
Article Tools
●
●
●
●
Add to Personal
Folders
E-Mail This Page
Print This Page
Share this article:
❍
Del.icio.us
❍
❍
Digg it!
Submit to
Slashdot
Previous Article | Next Article
Related Content
Enlarge Image
Search Google Scholar
for:
●
Articles by
Youngsteadt, E.
ADVERTISEMENT
Search PubMed for:
●
Articles by
Youngsteadt, E.
Search ScienceNOW
Keyword SearchEnter
Keyword
ADVERTISEMENT
●
●
Advanced Search
Science Magazine
My Science
●
●
●
●
Sensible snoozers.
New data show that sloths sleep only about half as much as previously believed.
Credit: Bryson Voirin
My Folders
My Alerts
Sloths Aren't So Slothful After All
My Saved Searches By Elsa Youngsteadt
ScienceNOW Daily News
Sign Out
14 May 2008
About Access
ScienceNOW articles are free for
four weeks after publication. Older
articles from the archive may
require AAAS membership or
separate subscription.
Alerts & Feeds
●
●
Email Alerts
RSS Feeds
It's time to retract those disparaging comments about sloths: They actually
don't sleep all the time. Sloths are certainly not insomniacs, but a new
miniature brain-recording device shows that, in nature, the animals snooze a
respectable 9.6 hours per day.
Researchers previously believed that sloths slept nearly 16 hours per day. That figure was based on
studies of captive sloths using electroencephalograms (EEGs), which detect brain activity associated with
slumber. The animals might sleep differently in nature, but good luck keeping a wild sloth wired to the
usual heavy EEG equipment.
Enter the portable EEG recorder. Developed in part by neurophysiologist Alexei Vyssotski of the
University of Zürich, Switzerland, the apparatus is housed in a cap that fits on top of an animal's head.
Small wires placed just under the skin of the scalp detect brain waves and send the numbers to a data
logger hidden inside the device.
http://sciencenow.sciencemag.org/cgi/content/full/2008/514/2 (2 of 3)11/1/2008 8:19:13 AM
Sloths Aren't So Slothful After All -- Youngsteadt 2008 (514): 2 -- ScienceNOW
New on Science Signaling
●
●
●
●
DAP12 Signals for
Macrophage Fusion
High Resolution
Imaging of Redox
Signaling
Call for Papers
More from Science
Signaling
Career Tools:
●
●
●
Find a Job
Find a Grant
Find a Meeting/
Event
A team led by Niels Rattenborg, a sleep researcher at the Max Planck Institute for Ornithology in
Starnberg, Germany, caught three brown-throated three-toed sloths (Bradypus variegatus) in Panama and
installed the mini EEG recorders, a process that took about 1 hour per animal. After 5 days, the
researchers tracked down the sloths and retrieved the data loggers. "The thing that really astonished us,"
Rattenborg says, "was that they slept just nine and a half hours per day."
It's not obvious why sloths would sleep less in nature than they do in captivity. The need to find food and
look out for predators could be one reason. Alternatively, boredom or depression might increase sleep in
captivity. The authors also note that the EEGs of captive sloths included some young animals, which may
have needed more sleep than the adults in this study.
Rattenborg, whose team reports its findings online 14 May in Biology Letters, says the technology could
be used to accurately gauge just how much sleep wild animals are getting. As with sloths, most of what
we know about animals' napping habits comes from studies of their captive counterparts. Such data could
be misleading, Rattenborg says, hindering efforts to understand the function of sleep in humans and other
animals.
Chiara Cirelli, a sleep researcher at the University of Wisconsin, Madison, says the study is a "wonderful"
proof that it's possible to get high-quality EEG data from sleeping wild animals. The method might also
be used to gauge sleep intensity, she says, another important measure for understanding the function of
sleep. "We just need many, many more" studies like this, says Cirelli. Rattenborg and his team are up to
the challenge: Ostriches are next.
Related sites
●
●
Vyssotski's site, with more info on his neurologgers
More on the evolution of sleep
New Articles on Careers
●
●
●
Pathways to
Independence
Award: Early
Returns
The Other Life
Sciences Industry
More Careers
Articles
To Advertise | Find Products
Magazine | News | Signaling | Careers | Multimedia | Collections | Help | Site Map | RSS
Subscribe | Feedback | Privacy / Legal | About Us | Advertise With Us | Contact Us
© 2008 American Association for the Advancement of Science. All Rights Reserved.
AAAS is a partner of HINARI, AGORA, PatientInform, CrossRef, and COUNTER.
You have reached the bottom of the page. Back to top
http://sciencenow.sciencemag.org/cgi/content/full/2008/514/2 (3 of 3)11/1/2008 8:19:13 AM