Celebrities and regular folk are plunging into frigid water for their social media feeds, but the science on the supposed benefits is lukewarm. Celebrities and regular folk are plunging into frigid water for their social media feeds, but the science on the supposed benefits is lukewarm. (AP Photo/Erin Hooley)The coolest thing on social media these days may be celebrities and regular folks plunging into frigid water or taking ice baths. ADVERTISEMENTTHE MINDYou might call Dan O’Conor an amateur authority on cold water immersion. Cronenwett says cold water immersion stimulates the part of the nervous system that controls the resting or relaxation state.