If you saw Leo Dio half freeze to death in The Revenant, you might have noticed what a healthy glow he had to him. That, dear reader, is the restorative power that sub-zero temperatures can have on the body, and is exactly what these clever sorts have managed to bottle up and offer in a safe environment (for a hefty premium). Step into their chamber (that looks like something out of an early Doctor Who episode) and you’ll be immersed in a cloud of -150 degree nitrogen. Because it’s dry the cold can't permeate your body, but your skin freaks out anyway and triggers your natural defences. All your blood rushes from your extremities to be filled with a whole mess of nutrients and anti-inflammatory things that are then slowly released back to the rest of your body once your brain realises that you are not, in fact, about to freeze to death. It’s a weird experience that leaves you feeling very aware of your blood flow but alert and awake. It's also great for muscular recovery, aches, pains and dodgy joints and can apparently help you sleep better. As is often the way with these things, however, you wanna do it regularly to get the full benefits. But at around 90 quid a pop, it’s not a cheap habit to maintain.