Cold exposure boosts the release of norepinephrine, which as a neurotransmitter is involved in focus, attention and mood. It inhibits inflammation by decreasing the signaling protein TNFα. Norepinephrine also acts as a hormone, promoting vasoconstriction and thus decreasing the total surface area by which heat is lost to its surroundings.The greater the jump in temperature, the more norepinephrine is released. It follows that going from hot to cold repeatedly, augments the concomitant health benefits. The effect is thought to be more pronounced with more extreme swings, as when alternating between ice bath and sauna. Research on this is lacking, and conclusive findings have yet to be established.