Something I didn't know either! I asked my Doctor why do I and other people urinate (pee) so much at night time.
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Answer from my Cardiac Doctor = Gravity holds water in the lower part of your body when you are upright. When you lie down and the lower body (legs and other things) seeks level with the kidneys it is then that the kidneys remove the water because it is easier.
I knew you need your minimum water to help flush the toxins out of your body, but this is news to me.
1 glass of water 30 minutes before a meal - helps digestion
1 glass of water before taking a bath - helps lower blood pressure
1 glass of water before going to bed - avoids stroke or heart attack
My Physician told me that water at bed time will also help prevent night time leg cramps. Your leg muscles are seeking hydration when they cramp and wake you up with a Charlie Horse.
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(Courtesy of forwarded mail from Khor Kean Kar)