Thermal acclimation of neonates to prolonged cool exposure as regards sleep stages.
The thermal responses of neonates during a cool acclimation period were studied with regard to sleep stages. Sleep stages, body temperatures and metabolic rate (VO2) were studied for seven neonates nursed in incubators and exposed to a cool temperature (thermoneutrality minus 2 degrees C) for 75 h. Each recording session lasted 3 h in the morning: firstly under thermoneutral baseline conditions, then during the first and last 3-h periods of the cool acclimation and finally during the last 3 h of a 24-h recovery period. Sleep structure was modified during the initial hours of cool exposure: the percentage of active sleep increased (AS: +13%, P = 0.028) at the expense of quiet sleep (QS: -11%, P = 0.043). This alteration in sleep structure persisted at the end of the acclimation period. Metabolic heat production only increased in the later period of cool acclimation. Throughout the cool exposure, VO2 increased more (P = 0.040) in QS (+33%) than in AS (+20%) so that by the end of the cool period, VO2 levels were similar in both sleep stages. During cool acclimation, the maintenance of homeothermy is related not only to a change in sleep organization but also to modifications in the thermoregulatory processes in both sleep stages. Considering the importance of AS/QS patterns in the neurobehavioral development of neonates, the present results could have clinical implications for the thermal management of neonates.
Telliez
Frédéric
F
Laboratoire d'Environnement Toxique Périnatal et Adaptations Physiologiques et Comportementales (EA 2088 INERIS-UPJV), Faculté de Médecine, Université de Picardie Jules Verne, AMIENS, France. frederic.telliez@sa.u-picardie.fr
Chardon
Karen
K
Leke
André
A
Cardot
Virginie
V
Tourneux
Pierre
P
Bach
Véronique
V
D000222:Adaptation, Physiological / Q000502:physiology*; D001481:Basal Metabolism / Q000502:physiology*; D001831:Body Temperature / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology*; D003080:Cold Temperature; D002149:Energy Intake; D004781:Environmental Exposure; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D010101:Oxygen Consumption / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology*; D013997:Time Factors