Strain difference in early postnatal sleep-wake behaviour between Alko Alcohol and Wistar rats.

Early postnatal sleep-wake behaviour of male and female rats of Alko Alcohol and Wistar strain was studied using a static charge sensitive mattress when the rats were aged 1 and 2 weeks postnatally. In both strains and sexes, waking time relative to total recording time increased, proportion of quiet state did not change, and that of active sleep decreased during the second postnatal week. The number of long active sleep stages relative to short active sleep stages and the duration of sleep-wake stages increased with age. Transitions between quiet state and active sleep became fewer with increasing age. Waking time increased more in Wistar rats than in Alko Alcohol rats. At 1-2 weeks of age, the percentage of active sleep and the number of long active sleep stages relative to short active sleep stages were larger, and the duration of sleep-wake stages longer in Alko Alcohol than in Wistar rats. Sleep-wake behaviour did not differ between the sexes of either strain or age. Selective breeding for high alcohol preference in Alko Alcohol rats may have caused a genetic trait in early postnatal sleep-wake behaviour.