A diallel analysis of the genetic underpinnings of mouse sleep

Abstract

Four highly inbred mouse strains were crossbred in all possible combinations. Five young adult males in each of the four original and twelve offspring groups were chronically implanted with cortical, hippocampal and nuchal electrodes and recorded for 24 hr. Significant genetic differences were found in total sleep, total paradoxical sleep, the number of short sleep episodes, the number of long sleep episodes and the diurnal ratio of total sleep, i.e., some parent strains reliably produced increases in these parameters in hybrids, whereas others produced decreases. Generally, these sleep indices were uncorrelated with each other. No evidence was found for sex-linkage or early maternal environmental effects on sleep. Paradoxical sleep, the number of long and short sleep episodes and the diurnal ratio of total sleep showed overdominance, i.e., hybrid amounts exceeded those of both parents, suggesting that the overall fitness of the mouse in its wild base population was augmented by a selection for more total sleep, less fragmentation, more even distribution of sleep and less paradoxical sleep.