Good point, but it looks like there's still a big effect. Vasoconstriction causes up to an extra 10 degC temperature gradient across the skin compared to when t

Good point, but it looks like there's still a big effect. Vasoconstriction causes up to an extra 10 degC temperature gradient across the skin compared to when they're dilated (less than 1 degC). [ http://www.healthyheating.com/Thermal_Comfort_Working_Copy/downloads/http___repositories.cdlib.org_cgi_viewcontent.pdf http://www.healthyheating.com/Thermal_Comfort_Working_Copy/d... p572 ] So that halves heat flow rate from what I described. It's like being in a 10 degC environment instead of 0 degC. You could double the length of the cold shower to 5 minutes to compensate.