The sleeping brain visualized by positron emission tomography Metabolic activity in the brain while awake and during sleep can be tracked according to glucose consumption by using positron emission tomography (PET). In general, red areas in PET scans indicate regions of highest metabolic activity, where neurons are consuming the largest amounts of glucose. (more) Why Is Sleep Important? Written by Kara Rogers Kara Rogers is the senior editor of biomedical sciences at Encyclopædia Britannica, where she oversees a range of content from medicine and genetics to microorganisms. She joined Britannica in 2006 and... Kara Rogers Fact-checked by Britannica Editors Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... Britannica Editors Last updated Feb. 17, 2026 •History Sleep is a cornerstone of human health, a window of time in which the body repairs itself, memories are consolidated, and vital systems are brought back into balance. This period of quiet restoration is an essential part of life, for adults and especially for children and teens, in whom sleep supports growth and development, particularly through nighttime hormone release. To reap the full benefits of sleep, individuals must experience sufficient, quality sleep each night. The...

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