Uncovering the evolution of REM sleep: Ostriches sleep like platypuses
(PhysOrg.com) -- The brain activity of ostriches in REM sleep is unique, alternating between fast, small waves - characteristic of REM sleep in other birds, and large, slow waves typical of those occurring during slow wave sleep. Moreover, the amount of REM sleep in ostriches is greater than in any other bird species. In collaboration with an international team, John Lesku and Niels Rattenborg from the Max Planck Institute for Ornithology in Seewiesen showed that these flightless birds possess a sleep pattern similar to that in the platypus, an ancient mammal that produces eggs. Apparently during the evolution of sleep the two distinct sleep states arose from a single heterogeneous state. Thereby REM sleep represents an evolutionarily new feature.