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.
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Thanks
to Public Library of Science for this article.