SLEEP IN THE HARP SEAL (PAGOPHILUS-GROENLANDICA) - PECULIARITIES OF SLEEP IN PUPS DURING THE 1ST MONTH OF THEIR LIVES

Two white-coated (ten day-old) and two grey-spotted (one month-old) pu ps of the harp seal were implanted with electrodes for recording the e lectrocorticograms of the two hemispheres, electrocardiogram, electroo culogram and electromyogram of the neck muscles. In all individuals EC oG slow waves always developed synchronously in both hemispheres. When white and grey pups were recorded on the snow, the amount of active w akefulness was, respectively, 21.1% (s.e. 11.8%) and 29.9% (s.e. 0.2%) of total recording time, quiet wakefulness = 27.1% (s.e. 4.4%) and 38 .2% (s.e. 6.6%), drowsiness=7.7% (s.e. 0.5%) and 2.07% (s.e. 0.9%), li ght slow-wave sleep (SWS) = 15. 1 % (s.e. 3.2%) and 13.0% (s.e. 2.4%), deep SWS = 21.2% (s.e. 2.4%) and 13.8% (s.e. 3.8%), paradoxical sleep (PS)=8.0% (s.e. 1.4%) and 7.4% (s.e. 1.1%). PS always followed SWS an d was fragmented. Respiration was very rare and irregular in PS and a considerable part of PS episodes occurred within a single respiratory pause. During SWS all pups displayed respiratory pauses of up to three minutes, alternating with hyperventilation periods. Heart rate was lo west in PS. Peculiarities of sleep and the pace of sleep pattern devel opment during the first month in seals may be adaptive to the cold env ironment and ice field drifting in their habitat.