Scientific Understanding of Consciousness
Consciousness as an Emergent Property of Thalamocortical Activity

Sleep Necessity



Why We Sleep: The Temporal Organization of Recovery

Citation: Mignot E (2008) Why We Sleep: The Temporal Organization of Recovery. PLoS Biol 6(4): e106. doi:10.1371/journal.pbio.0060106

Emmanuel Mignot is at the Howard Hughes Medical Institute and the Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, California,

Published: April 29, 2008


If sleep does not serve an absolutely vital function, then it is the biggest mistake the evolutionary process has ever made, Allan Rechtschaffen said. Studies of sleep and sleep deprivation suggest that the functions of sleep include recovery at the cellular, network, and endocrine system levels, energy conservation and ecological adaptations, and a role in learning and synaptic plasticity.

Sleep is as necessary as water and food, yet it is unclear why it is required and maintained by evolution. Recent work suggests multiple roles, a correlation with synaptic plasticity changes in the brain, and widespread changes in gene expression, not unlike what has been recently discovered in circadian biology. Functional data are however still largely lacking, and studies such as functional genomic screens in model organisms, comparative sleep neuroanatomy through phylogeny, and the study of molecular changes within specific wake, REM sleep, and NREM sleep regulatory systems are needed. The resilience of behavioral sleep in evolution and after experimental manipulations may be secondary to the fact that it is grounded at the molecular, cellular, and network levels.

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