PerspectiveSleep

Measuring the passage of brain time

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Science  12 Aug 2016:
Vol. 353, Issue 6300, pp. 648-649
DOI: 10.1126/science.aah5402

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Summary

The brain's central circadian (near-24-hour) clock exerts a very powerful influence on sleep and wakefulness (1, 2), interacting with our increasing drive to sleep as time awake increases (3, 4). On page 687 of this issue, Muto et al. (5) demonstrate that the interaction of the circadian clock with this so-called homeostatic sleep drive—which had been inferred from studies of human performance, sleep propensity, and risk of error or accident (3, 4, 6)—is rooted in measurable changes in cortical and subcortical responsiveness. Moreover, the nature of the interaction varies among cortical and subcortical brain regions.