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Tears contain an important hormone that kills bacteria. Closing eyelids during sleep allows a prolonged contact between the cornea and tears killing resistant bacteria in the process. The action of the tears during blinking is not sufficient to completely get rid of the foreign bodies in the eyes. Closing eyelids gives the tears a capacity to accumulate ...


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We don't actually know. But these two theories are strong candidates: Sleep 'cleans' the brain of toxins. Metabolic waste products of neural activity are cleared out of the sleeping brain at a faster rate than during the awake state. This finding suggests a mechanistic explanation for how sleep serves a restorative function, in addition to its ...



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