From the New York Times, July 4, 2015
"Enduring Summer’s Deep Freeze" by Kate Murphy,
". . . . As infants we learn to associate warmth with the safety of our parents’ arms. Our subconscious equates cold with vulnerability, which partly explains why people can be so miserable when they are chilled.
A region of the brain called the hypothalamus is responsible for our body’s thermoregulatory system, constricting blood vessels when we are cold and dilating them when we are hot to maintain a safe core body temperature. Your physical discomfort is essentially the hypothalamus prodding you to say, put on a sweater if it’s chilly or fan yourself when it’s hot.
Extreme temperature changes like entering a freezing lobby on a sweltering summer day may feel good at first, but it makes the hypothalamus go nuts, intensifying physical and psychological discomfort when the initial pleasure wears off — as if to say: “A blizzard is on its way! Do something!”
“It’s left over from a time when it was dangerous to have that kind of change in temperature,” said Nisha Charkoudian, a research physiologist with the United States Army Research Institute of Environmental Medicine in Natick, Mass. . . . "