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 as it is now 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. I did this yesterday and it really helped.
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.