Apr 4, 2008

Phylogenetic analysis of the ecology and evolution of mammalian sleep

Evolution; International Journal of Organic Evolution
Isabella CapelliniCharles L Nunn


The amount of time asleep varies greatly in mammals, from 3 h in the donkey to 20 h in the armadillo. Previous comparative studies have suggested several functional explanations for interspecific variation in both the total time spent asleep and in rapid-eye movement (REM) or "quiet" (non-REM) sleep. In support of specific functional benefits of sleep, these studies reported correlations between time in specific sleep states (NREM or REM) and brain size, metabolic rate, and developmental variables. Here we show that estimates of sleep duration are significantly influenced by the laboratory conditions under which data are collected and that, when analyses are limited to data collected under more standardized procedures, traditional functional explanations for interspecific variation in sleep durations are no longer supported. Specifically, we find that basal metabolic rate correlates negatively rather than positively with sleep quotas, and that neither adult nor neonatal brain mass correlates positively with REM or NREM sleep times. These results contradict hypotheses that invoke energy conservation, cognition, and development as drivers of sleep variation. Instead, the negative correlations of both sleep states with basal metab...Continue Reading

  • References37
  • Citations52


  • References37
  • Citations52


Mentioned in this Paper

Computer Software
Laboratory Procedures
Sleep, Slow-Wave
Energy Metabolism
Equus asinus
Eye Movements
Morphologic Artifacts

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