There are a few things people live without: oxygen, food, water and sleep. This almost certainly applies to all mammals including humans. Sleep be doing something very important, scientific studies convincingly suggest. But there is no unanimous opinion on this issue. Scientists know that sleep help process and sort out our memories. It is a true possibility that sleep put our emotions back on track again. There is some weak evidence that sleep have a healing effect on the body. There is a recommendation that people sleep much because it is a waste of time to lose consciousness every sixteen hours. But the fact that people do without sleep and to drop off regularly strongly suggests that there be something very important in this biological state. There is a weak possibility that those with a sound sleep be a little healthier than those with insomnia.

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There are a few things people [can|can't|must|mustn't] live without: oxygen, food, water and sleep. This almost certainly applies to all mammals including humans. Sleep [must|can't|shouldn't|might] be doing something very important, scientific studies convincingly suggest. But there is no unanimous opinion on this issue. Scientists know that sleep [may not|can|should|need] help process and sort out our memories. It is a true possibility that sleep [may|needn't|must|can't] put our emotions back on track again. There is some weak evidence that sleep [may not|can|shouldn't|might] have a healing effect on the body. There is a recommendation that people [should|shouldn't|can|can't] sleep much because it is a waste of time to lose consciousness every sixteen hours. But the fact that people [should|shouldn't|can|can't] do without sleep and [must|mustn't|need|needn't] to drop off regularly strongly suggests that there [must|mustn't|need|needn't] be something very important in this biological state. There is a weak possibility that those with a sound sleep [should|mustn't|might|can't] be a little healthier than those with insomnia.