The echidna Tachyglossus aculeatus combines REM and non-REM aspects in a single sleep state: implications for the evolution of sleep.

TitleThe echidna Tachyglossus aculeatus combines REM and non-REM aspects in a single sleep state: implications for the evolution of sleep.
Publication TypeJournal Article
Year of Publication1996
AuthorsSiegel, JM, Manger PR, Nienhuis R, Fahringer HM, Pettigrew JD
JournalThe Journal of neuroscience : the official journal of the Society for Neuroscience
Volume16
Issue10
Pagination3500-6
Date Published1996 May 15
ISSN0270-6474
KeywordsAnimals, Behavior, Animal, Cats, Dogs, Echidna, Electroencephalography, Female, Male, sleep, Sleep, REM
Abstract

Placental and marsupial mammals exist in three states of consciousness: waking, non-REM sleep, and REM sleep. We now report that the echidna Tachyglossus aculeatus, a representative of the earliest branch of mammalian evolution (the monotremes), does not have the pattern of neuronal activity of either of the sleep states seen in nonmonotreme mammals. Echidna sleep was characterized by increased brainstem unit discharge variability, as in REM sleep. However, the discharge rate decreased and the EEG was synchronized, as in non-REM sleep. Our results suggest that REM and non-REM sleep evolved as a differentiation of a single, phylogenetically older sleep state. We hypothesize that the physiological changes that occur during postnatal sleep development parallel certain aspects of the changes that have occurred during the evolution of sleep-waking states in mammals.

DOI10.1111/j.1365-2869.2012.01023.x
Alternate JournalJ. Neurosci.