Remember the ice-bucket challenge of 2014?

It saw Simon Cowell, Tom Cruise, Taylor Swift and other celebrities having buckets of cold water poured on their heads to show their support for Amyotrophic Lateral Sclerosis (ALS), the US charity for motor neurone sufferers that instigated the latest internet craze.

But, as we often suspect with the rich and famous, they’re probably not acting purely out of altruism; the health and beauty wonders of some freezing water are endless.

[Read more: How much water do you drink? 8 things you should know about dehydration]

How do we know?

Firstly, David Beckham drenched himself, and no one could possibly argue with how healthy and beautiful he is.

But secondly, because cold water is simply very good for you. And here’s why…

Cold water burns calories

If you jump into a cold shower, your body instantly works to get it back up to its normal temperature – as it does this, your metabolism can increase by up to 550% of its resting level, burning calories in the process.

Drinking cold water is thought to have a similar effect, so if you don’t want to be under icy water, at least put it in you.

Cold water gives you glowing skin…

Hot water strips your skin of essential oils, but cold water does the opposite. It also gives you a healthy glow by encouraging blood to rush to the skin’s surface.

Contrary to popular belief, it doesn’t actually make pores smaller – that’s all set in your genes – but two out of three ain’t bad.

…And shiny hair

It takes a brave soul to wash their hair in cold water, but also a sensible and shiny soul. Cold water makes the cuticles of your hair lie flatter, and this in turn reflects more light.

[Read more: The biggest ice bucket challenge yet – video]

Cold water wakes you up

And not just in a comedy bucket-in-the-face sort of way. Cold water activates cold sensors just under our skin, which then increase our heart rate and add a surge of adrenaline to give you that jittery (but good) alive feeling.

It makes you happy

Ice-cream is scientifically proven, by neuroscientists at the Institute of Psychiatry in London, to make people happy, stimulating the orbitofrontal cortex (or ‘enjoyment bit’) of the brain. It is veering a little off track, but if ice-cream can make you happy, then we’ll wager ice-water can too.

Or you could just have an ice-cream, obviously.

Cold water eases pain

Adrenaline not only makes you feel more alive, it makes you feel more pain-free by cleverly distracting our brain from niggling aches. The effect can last longer-term too: rugby players sit in ice baths after matches; the cold water reduces blood flow to the muscles before taking then out of the ice allows them to fills back up with new, less lactic acid-filled blood.

Cold water boosts your immune system…

A few years ago, a German study revealed people who showered for two minutes in cold water developed fewer colds than those who took a hot shower. Why? Because the mild stress makes your immune system think it should be doing something and gives it a mini ‘workout’.

[Read more: 6 easy ways to drink more water]

This theory is backed up by Czech scientists who discovered that those who immersed themselves in cold water three times a week had a much higher level of white blood cells (the ones that fight infection) than those who didn’t.

…And your sex life

Forget all that nonsense about things ‘hotting up’, you need to be cooling it down. Being in cold water is thought to improve levels of the sex hormones testosterone and oestrogen.