It's often thought that these nighttime urges are linked to drinking fluids late at night. In reality, another mechanism frequently comes into play: the redistribution of bodily fluids.
During the day, especially if you sit or stand for long periods, some fluids accumulate in the legs and ankles. This phenomenon often goes unnoticed. But once you lie down, these fluids return to the bloodstream. The kidneys then filter this excess… and the bladder fills more quickly during the night.
This mechanism, called nocturnal polyuria , becomes more common with age, but can affect different individuals.
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