If you had to assign one attribute to the kind of people who jump into ice-encrusted lakes for fun, it would probably be: weird. But, if pushed for a second, I bet it would be: healthy.

1. Boosts your immune system
For your body, a sudden and drastic change in temperature constitutes an attack – as anyone who’s ever fallen overboard in British waters will concur. And, whilst “attacking” your own body may not sound like a good thing, there is no harm in keeping it on its toes. In fact, quite the opposite.

Scientists from the Czech Republic immersed witting subjects in cold water for one hour, three times a week and monitored their physiology. They found significant increases in white blood cell counts and several other factors relating to the immune system. This was attributed to the cold water being a mild stressor which activates the immune system and gives it some practice.

2. For an all-natural high
Winter swimmers talk a lot about the ‘high’ they get from cold water – a feeling of wellbeing that’s so encompassing that it becomes quite addictive (who doesn’t want to feel truly good, at least once a day?) The cause? Endorphins.

Endorphins are the body’s natural pain killers and, in the case of a cold dip, it uses them to take the sting away from your skin. So, to get high on your own supply, all you need to do is jump in a river.

And if you think that sounds dangerously close to the pleasure/pain barrier then you’re probably right. The two other primary causes for endorphin release are pain and orgasm.

The cold will also stimulate your parasympathetic system, which is responsible for rest and repair, and this can trigger the release of dopamine and serotonin. These neurotransmitters are a vital part of keeping us happy and low levels of them are linked with depression. Couple this effect with the endorphin rush as you take the plunge and it should make for a warm glow and a wide smile when you re-emerge.

3. Gets your blood pumping
Being hot brings blood to surface. Being cold sends it to your organs. Both extremes work your heart like a pump. That’s why the whole sit in the sauna, roll in the snow, sit in the sauna thing makes people glow. But why is increased blood flow good for you?

Well, it helps flush your circulation for starters, pushing blood through all your capillaries, veins and arteries. It will exfoliate your skin and flush impurities from it, thus helping your complexion (firm-bodied women of all ages around pool sides say it stops cellulite). Evidence also demonstrates that your body adapts to the cold with repeated exposure and this may improve your circulation, particularly to your extremities – no bad thing in the winter months.

You could get these benefits by switching between the hot and cold taps in your shower (or the sauna, snow, sauna thing) but that doesn’t sound nearly as fun as quick dip in your local lake followed by wrapping up warm afterwards.