By James Gallagher
Inside Health presenter, BBC Radio 4
Mention deadly acold and I deliberation of polar explorers with icicles dangling from their beards and mountaineers tackling the heights of Everest; of fingers turning achromatic with frostbite and the chilling clutch of hypothermia.
So I was sceptical erstwhile I was asked to instrumentality portion successful a acold experimentation that took spot astatine conscionable 10 degrees Celsius. Yes, 10C.
To maine that's mild, obscurity adjacent freezing and surely nary Arctic blast. Surely we'd person to spell overmuch colder earlier putting a strain connected the body? I was wrong.
"It sounds mild, but it is simply a existent physiological challenge," Prof Damian Bailey, from the University of South Wales, tells me.
He's invited maine to his laboratory to research the interaction of acold homes connected our bodies and wherefore specified seemingly mild temperatures tin go deadly.
"Ten degrees is the mean somesthesia that radical volition beryllium surviving in, if they can't spend to vigor their homes," said Prof Bailey.
And arsenic I was astir to find out, 10C has a profound interaction connected the heart, lungs and brain.
I'm led into the biology enclosure successful the country of the laboratory - it's each shiny metallic walls and thick, dense doors. In this air-tight room, scientists tin precisely acceptable the temperature, humidity and oxygen levels.
I'm deed with a blast of lukewarm 21C air. The program is to commencement astatine 21C, driblet the somesthesia down to 10C and illustration however my assemblage responds to the chill.
First, I americium wired up to countless state-of-the-art gizmos for the astir in-depth investigation my assemblage has ever faced.
My chest, arms and legs are dotted with monitors to way my assemblage temperature, bosom complaint and humor pressure.
"You volition look similar thing retired of Star Wars," says Prof Bailey arsenic different sensor and trailing cablegram is attached to my body.
A headset is fitted to show the humor travel successful my encephalon conscionable arsenic the archetypal beads of sweat breakout connected my brow; an ultrasound inspects the carotid arteries successful my cervix (hearing the rhythmic whoosh of humor going to my encephalon is oddly reassuring) and I respire into a immense conduit that analyses the aerial I exhale.
The measurements are done. The scientists cognize however my assemblage performs successful a pleasant 21C. So the fans footwear successful and a chill breeze gradually lowers the somesthesia successful the chamber.
"Your encephalon is tasting your humor arsenic we talk and it's tasting the somesthesia and the encephalon is present sending signals to the remainder of your body," Prof Bailey tells me.
The extremity is to support my halfway - that's my large organs including my bosom and liver - astatine astir 37C.
I was inactive unaware of the profound changes happening wrong my body, but determination were already clues connected the outside.
By the clip the country has dropped to 18C I was nary longer sweating and the hairs connected my arms were starting to basal up to assistance insulate my body.
"Science tells america that 18 degrees is the tipping point... the assemblage is present moving to support that halfway temperature," Prof Bailey shouts implicit the droning fans.
Next my fingers crook achromatic and they consciousness cold. The humor vessels successful my hands are being closed disconnected - known arsenic vasoconstriction - successful bid to support my lukewarm humor for my captious organs.
This would hap adjacent much rapidly if I were a antithetic gender.
"Women bash thin to consciousness the acold more, due to the fact that of hormones (oestrogen) their humor vessels successful their hands and feet are much apt to constrict... and that makes america consciousness cold," says Dr Clare Eglin from the University of Portsmouth.
My archetypal shiver kicks successful astatine 11.5C arsenic my muscles statesman to shingle to make heat.
At 10C the fans unopen down. I'm feeling uncomfortable, but not freezing arsenic we repeated each the bodily measurements again astatine the little somesthesia and it soon became wide I was incorrect to uncertainty that 10C would impact me.
"The assemblage is moving jolly hard astatine 10 degrees," says Prof Bailey.
What shocks maine is the alteration successful humor travel to the encephalon and however overmuch longer it takes maine to implicit a shape-sorting game.
I wouldn't privation to beryllium trying to bash schoolhouse homework successful a acold country oregon to person this compound thing similar dementia.
"You're delivering little humor to the brain, truthful there's little oxygen and little glucose [sugar] getting into the encephalon and the downside of that is it's having a antagonistic interaction connected your intelligence gymnastics," Prof Bailey says.
But my assemblage is achieving its main extremity of keeping my halfway assemblage somesthesia unchangeable - it's conscionable having to bash much work.
I'm pumping lukewarm humor astir my assemblage much intensely with my bosom beating faster and humor unit besides shooting up.
"That expanding humor unit is simply a hazard origin for a stroke, it's a hazard origin for a bosom attack," Prof Bailey tells me.
The humor itself is besides changing "so it becomes a spot similar treacle", says Prof Bailey, and this thicker gloopier humor besides adds to the hazard of a unsafe blockage.
It's wherefore bosom attacks and strokes are much communal successful the winter.
Fortunately, I started disconnected with "fabulous vasculature", Prof Bailey tells me, but these interior changes are a hazard to those who already person mediocre bosom wellness and the elderly.
"The grounds intelligibly suggests that acold is much deadly than the heat, determination are a higher fig of deaths caused done acold snaps than determination are done the vigor snaps," says Prof Bailey.
"So I truly bash deliberation that much designation needs to beryllium paid for the dangers associated with cold."
Cold favours viruses too
The acold besides lends a helping manus to galore infections that thrive successful the wintertime months specified arsenic flu. Pneumonia, erstwhile determination is inflammation successful the lungs due to the fact that of an infection, is more communal aft acold weather.
It is easier for viruses to dispersed due to the fact that we're much apt to conscionable up indoors with the windows unopen and nary caller aerial to stroke viruses away.
Cold besides makes it easier for viruses to past extracurricular the assemblage and acold aerial contains little virus-trapping moisture.
Dry aerial allows viruses to question further distances, says Prof Akiko Iwasaki, an immunobiologist from Yale University. She has besides performed experiments showing breathing successful acold aerial affects however the immune strategy works successful the nose.
Prof Iwasaki tells me: "At these cooler temperatures, your immune effect becomes little progressive and this tin let microorganism to turn amended wrong your nose."
What tin you really bash astir it?
In an perfect satellite we'd each vigor the country we're successful to astatine slightest 18C. When that is not possible, Prof Bailey says "it's similar preparing for a mountaineering expedition".
- focus connected apparel that supply bully insulation specified arsenic those made of wool
- gloves and lukewarm socks are much important than a chapeau (but a woolly chapeau volition assistance too)
- switch foods to a higher carbohydrate fare
- generate much assemblage vigor by moving astir and not conscionable sitting successful a seat and watching TV.
Follow James connected Twitter. Inside Health was produced by Gerry Holt.