I really love being in water. My special physiotherapist explained that the pressure of water helps to bring about a balance between the sympathetic and parasympathetic nervous systems. I think it's because it calms the sympathetic system. She said water's best for this condition at 33degrees. I know 22-24 degrees is less than ideal but I love swimming in summer and I figure the endorphin raising power of having fun wins out. When it's still too cool to swim and as there is no heated pool nearby, I soak in an epsom salts bath. While in the bath I breathe out twice as long as in which activates the parasympathetic nervous system adding to the benefit from water pressure and warmth for circulation.
Another thing I've discovered about water is that if I'm having whole body nerve firing and I drink a full big glass of water, it settles. I'm not sure why but it works for me.