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The Science Behind Dehydration

You might think this is a strange time to be discussing dehydration...

We all know it's important to drink water and stay hydrated when it's hot or we're exercising. We're hot and we're sweating: we know we're losing water.

However, did you know more dangerous dehydration is caused by cold weather, and it's more dangerous because we're not as aware it's happening. Whilst we were waiting around feeling cold, I realised I knew the science behind it (our memory is a funny thing!). Ready for it?

When we're cold, our body tries to regulate our temperature by minimising heat loss (this is called homeostasis - the maintenance of a constant internal environment). The cells of our body are able to generate heat through the chemical reaction respiration, and to warm up, the body tries to keep as much of this heat as possible.

It does this by shutting off the blood supply to our small blood vessels which are close to the skin (this is called vasoconstriction and that's why we can look pale when we're cold). This means more blood returns from the extremities (arms and legs), and there is more in the thorax, where your vital organs are.

This in turn increases the blood pressure in your thorax, which is detected by receptors called baroreceptors. To lower blood pressure, water is therefore excreted through the kidneys, meaning we often need a wee more when we're cold - and hence get dehydrated!

Now you know - so remember to keep up that water intake through the cold months ladies! That means only one thing for me as winter sets in… gallons of lovely hot tea (my favourites are green tea and lemon and ginger), preferably curled up in front of the fire in my dressing gown!! However in reality this weekend it meant bottles of water and revision notes on a train… whatever it takes!

What are your favourite ways of staying hydrated in the colder weather?


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