I am very delighted to read all the good positive stories about cold water shower healing. Allow me to share my story.
I am a Moslem (from Indonesia), and the month of Ramadhan (fasting) was just over. For those not familiar with this, Moslems fast for 30 days during the Ramadhan month, every day, wake up at dawn (around 3 AM), have meal, fast during the day (no drinking no eating no sex), and break the fast at around 6 PM.
I have this problem with my right leg knee, it gives me pain when I bend during a prayer. For one month of Ramadhan, I "practiced" the cold water shower each time I wake up, at around 2:30 AM. After that, I pray (the so called "night prayer"), and have meal. To the best of my knowledge there is no reference in Al Quran about taking shower at "night", although there is the so called "night prayer" which is not obligatory, but very strongly advised for Moslems, and it takes time somewhere between 2:30 and 3:30 AM. We call it the "last one-third of the night".
I just felt I had to heal myself this way, because I heard many times especially from elders and those "natives" coming from rural villages, of cold water shower "healing", which normaly takes time between 2 and 4 AM. Many people here say, it's not healthy to take shower at night, before 12 AM, but it's healthy if taken after say, 1 AM. Some martial arts practitioners here do take shower after evening/night training, at around 1-2 AM or later. I had a friend who literally couldn't walk, not paralyzed but pain in both his legs (thigh), was eventually healed, Praise Allah, could walk (and run) normally again after spending about a month or so taking cold water shower from a well (using bucket / dousing) every night (at around 3 AM).
Back to myself, Praise Allah, after 30 days of night cold water shower, I do feel better now. I can bend my knee again, with less pain.
Perhaps someone have an explanation about the "state" of water during the night, especially between 2 and 4 AM ?