System that controls sleep may be same for most mammals

In a novel mathematical model that reproduces sleep patterns for multiple species, an international team of researchers has demonstrated that the neural circuitry that controls the sleep/wake cycle in humans may also control the sleep patterns of 17 different mammalian species. These findings, reported by researchers from Brigham and Women's Hospital (BWH), the University of Sydney, and the Center for Integrated Research and Understanding of Sleep (Camperdown, Australia), suggest that fundamental physiological mechanisms are at work across diverse species, even though sleep patterns vary drastically. This research published June 24th in the open-access journal PLoS Computational Biology.

"These findings show that although mammalian sleep is remarkably diverse in expression, from dolphins who sleep with one brain half at a time to rodents who have many short naps, it is very likely universal in origin, which suggests that this simple system is both highly flexible and evolutionarily conserved," said Andrew Phillips, lead author of the paper and researcher in the Division of Sleep Medicine at BWH.

Over the past decade, researchers have reported findings related to the structures in the brain that are critical to sleep regulation, but these findings have been limited to a small number of species. Until now, it was unclear to what extent these physiological mechanisms are universal across all mammals, especially given such large interspecies differences in sleep patterns.

Using their model, the authors also provide insight into why the sleep patterns of different species are so distinct. For example, the model explains how some mammals (such as dolphins and seals) sleep with one half of their brain at a time while the other half remains active; if the sleep centers on either side of the brain inhibit one another then only one is able to activate at a time, preventing the animal from sleeping with both brain halves at once. This testable prediction awaits physiological investigation.

The authors stress that this research was performed using a mathematical model of the physiology to simulate the sleep patterns of different mammals. Further research is thus required to test these predictions directly, and to determine whether the same physiological mechanisms are at work in nocturnal species.

FINANCIAL DISCLOSURE: This work was supported by the Australian Research Council, the National Health and Medical Research Council, and the National Space Biomedical Research Institute through NASA NCC 9-58. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

COMPETING INTERESTS: The authors have declared that no competing interests exist.

PLEASE ADD THIS LINK TO THE PUBLISHED ARTICLE IN ONLINE VERSIONS OF YOUR REPORT: http://dx.plos.org/10.1371/journal.pcbi.1000826 (link will go live upon embargo lift)

CITATION: Phillips AJK, Robinson PA, Kedziora DJ, Abeysuriya RG (2010) Mammalian Sleep Dynamics: How Diverse Features Arise from a Common Physiological Framework. PLoS Comput Biol 6(6): e1000826. doi:10.1371/journal.pcbi.1000826

Lori Shanks
Brigham and Women's Hospital
ljshanks@partners.org
(617) 534-1604

Disclaimer

This press release refers to an upcoming article in PLoS Computational Biology. The release is provided by the article authors and Brigham and Women's Hospital. Any opinions expressed in this release or article are the personal views of the journal staff and/or article contributors, and do not necessarily represent the views or policies of PLoS. PLoS expressly disclaims any and all warranties and liability in connection with the information found in the releases and articles and your use of such information.

PLoS Computational Biology (www.ploscompbiol.org) features works of exceptional significance that further our understanding of living systems at all scales through the application of computational methods. All works published in PLoS Computational Biology are open access. Everything is immediately available subject only to the condition that the original authorship and source are properly attributed. Copyright is retained by the authors. The Public Library of Science uses the Creative Commons Attribution License.

The Public Library of Science (PLoS) is a non-profit organization of scientists and physicians committed to making the world's scientific and medical literature a freely available public resource. For more information, visit http://www.plos.org.