Originally Posted by joeandruth

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Periods of sleep can also change urine color in human beings. While I am not a fanatic toilet inspector, I have observed that the first urine passed in the morning is noticeably darker in color than urine passed during the day. Your kidneys do function differently in sleep, concentrating the urine so that you can go 8 or more hours without waking up to pee (unless of course you are a 74 year old male like me, with a prostate the size of a soccer ball).