title: Sleep and wakefulness in the southern sea lion.
abstract: We recorded an electroencephalogram from the two hemispheres, a neck musculature electromyogram, an electrooculogram, and respiratory acts during sleep and wakefulness on land in three 1-year-old sea lion females for 3 or 4 consecutive days. On average active wakefulness (AW) occupied 20.4+/-2.0% of the 24-h period; quiet wakefulness (QW) 54.9+/-2.5%; slow wave sleep (SWS) 15.0+/-2.5% and paradoxical sleep (PS) 9.7+/-2.0%. Between 30 and 50% (average 39.1+/-3.4%) of total sleep time was spent in PS. From 8 to 31 episodes of PS were recorded per day (average 17+/-6 per day), with the longest episode lasting 20 min (average 5.6+/-0.5 min). Episodes of interhemispheric EEG asymmetry accounted for 5.5+/-1.3% of total SWS time. Respiratory pauses in these animals varied in QW between 4 and 36 s (average 15.7+/-0.4 s), in SWS between 11 and 37 s (20.9+/-0.6 s) and in PS between 2 and 69 s (15.0+/-1.5 s). AW, QW, SWS and PS were approximately equally distributed between light (07:00-19:00) and dark time (19:00-07:00). The low amount of SWS with interhemispheric EEG asymmetry, the high proportion of PS in total sleep time and the nearly even distribution of sleep and wakefulness over the 24-h period could be both species-specific features and/or ontogenetic characteristics of the animals studied.
authors.affiliation: Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 33 Leninsky Prospect, 117071 Moscow, Russia. olyamin@ucla.edu
authors.forename: Oleg I
authors.initials: OI
authors.lastname: Lyamin
authors.forename: Lev M
authors.initials: LM
authors.lastname: Mukhametov
authors.forename: Igor S
authors.initials: IS
authors.lastname: Chetyrbok
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Vassiliev
mesh_terms: D000818:Animals; D003344:Cortical Synchronization; D004562:Electrocardiography; D004567:Electrodes, Implanted; D004569:Electroencephalography; D004576:Electromyography; D004585:Electrooculography; D005260:Female; D017286:Polysomnography; D046070:Sea Lions / Q000502:physiology*; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology; D014851:Wakefulness / Q000502:physiology*