title: Evolution of wakefulness, sleep and hibernation: from reptiles to mammals.
abstract: Thus far, most hypotheses on the evolutionary origin of sleep only addressed the probable origin of its main states, REM and NREM. Our article presents the origin of the whole continuum of mammalian vigilance states including waking, sleep and hibernation and the causes of the alternation NREM-REM in a sleeping episode. We propose: (1) the active state of reptiles is a form of subcortical waking, without homology with the cortical waking of mammals; (2) reptilian waking gave origin to mammalian sleep; (3) reptilian basking behaviour evolved into NREM; (4) post-basking risk assessment behaviour, with motor suspension, head dipping movements, eye scanning and stretch attending postures, evolved into phasic REM; (5) post-basking, goal directed behaviour evolved into tonic REM and (6) nocturnal rest evolved to shallow torpor. A small number of changes from previous reptilian stages explain these transformations.
authors.affiliation: Institut Universitari de Ciències de la Salut, Universitat de les Illes Balears, Palma de Mallorca, Spain. rvrial@uib.es
authors.forename: Ruben V
authors.initials: RV
authors.lastname: Rial
authors.forename: Mourad
authors.initials: M
authors.lastname: Akaârir
authors.forename: Antoni
authors.initials: A
authors.lastname: Gamundí
authors.forename: Cristina
authors.initials: C
authors.lastname: Nicolau
authors.forename: Celia
authors.initials: C
authors.lastname: Garau
authors.forename: Sara
authors.initials: S
authors.lastname: Aparicio
authors.forename: Silvia
authors.initials: S
authors.lastname: Tejada
authors.forename: Lluis
authors.initials: L
authors.lastname: Gené
authors.forename: Julián
authors.initials: J
authors.lastname: González
authors.forename: Luis M
authors.initials: LM
authors.lastname: De Vera
authors.forename: Anton M L
authors.initials: AM
authors.lastname: Coenen
authors.forename: Pere
authors.initials: P
authors.lastname: Barceló
authors.forename: Susana
authors.initials: S
authors.lastname: Esteban
mesh_terms: D000818:Animals; D005075:Biological Evolution; D006605:Hibernation / Q000502:physiology*; D006801:Humans; D012104:Reptiles / Q000502:physiology*; D012890:Sleep / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology*