CIRCADIAN-RHYTHM OF SLEEP IN THE KANGAROO RAT (POTOROUS APICALIS) - INFLUENCE OF FOOD DISTRIBUTION

The influence of food distribution on circadian rhythm of sleep was studied by polygraphic methods in 4 adult kangaroo rats and in 3 young from 18-19 wk old (at the weaning period). Experimentation was carried out in July-Aug. Animals were kept in isolation and in continuous light (LL) for 3 wk; food was given every day from 1900-2000h and it was available ad lib; therefore, the tested factor presented characteristics of a brief and punctual signal. In the adult Potorous, the persistency of alternate phases of activity and rest was observed. Their periodicity coincided approximately with that described in the light-dark schedule; that means an absence of phase change in the circadian rhythm of sleep in these animals. A decrement was observed in circadian variations of total sleep amount. An increase of both paradoxical and slow wave sleep percentages appeared during the subjective night of the animals. Young Potorous kept in (LL) from the 18th-21st wk after birth, presented some perturbations in their sleep-wakefulness cycle similar to those observed in adults. The young seem to answer individually to the periodic food distribution factor. The importance of food distribution for synchronizing biological rhythm in natural environmental conditions was discussed and its determinant value as a signal was revealed.