title: [The temporal characteristics of "winter" paradoxical sleep in the hibernating suslik Citellus major].
abstract: It has been shown that paradoxical sleep (PS) total time (TT) in euthermia phase of hibernation cycle (winter sleep) can be compared with its mean values in euthermia season. Ultradian fluctuations of PS episodes duration, TT and phase number as well as bradycardia microintervals are revealed in euthermia phase dynamics. Amplitude of these fluctuations increases before hibernation entry; in transitional "start" period PSTT increases up to maximum critical values. In hibernation cycle PSTT rapidly decreases at the first stage owing to reduction of PS phase number and their duration. These data support and supplement earlier suggested hypothesis about endogenous "swinging up" of ultradian rhythms of sleep and thermoregulation promoting stage-to-stage expansion of homeostasis temperature limits in various critical periods of preparation and entry of homeotherms into natural hypometabolic states (torpor, hibernation and others).
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000502:physiology; D005260:Female; D006605:Hibernation / Q000502:physiology*; D008297:Male; D017286:Polysomnography; D012589:Sciuridae / Q000502:physiology*; D012621:Seasons; D012895:Sleep, REM / Q000502:physiology*; D013997:Time Factors; D014851:Wakefulness / Q000502:physiology
vernacular_title: Vremennye kharakteristiki "zimnego" paradoksal'nogo sna u giberniruiushchego suslika Citellus major.