–it is very injurious, your dreams will be hideous, and you will not feel rested on arising.  It is dangerous to persons suffering from throat or lung troubles.  The temperature of your sleeping room should not be permitted to fall below 40° above zero.

but seldom, if ever, in water very warm or very cold–they both are injurious.  Warm water weakens and cold water chills.  The temperature of the water should be about the same as that of the body.