PROTECT YOURSELF BEFORE YOU WRECK YOURSELF

Combine the cold and dark of winter with the indulgence of the holiday season, and you have the ideal conditions for illness to strike. But there are ways to bolster your body's defences ahead of the onslaught - ways that rely on science's evolving understanding of our immune system

- by DR JENNA MACCIOCHI

Winter is the busiest season for your immune system. An onslaught of cold air, close contact and a crowded calendar that includes a party season filled with late nights, large meals and, possibly, a little too much liquor. Most of us only consider our immune systems when something goes wrong: the scratch in the throat, the fatigue, the inconvenient cold that hits just as the year speeds towards its end. We put it down to the chill in the air or 'bugs going around'. But those symptoms are an expression of one of the body's most astonishing networks, a mindbogglingly complex system that's sensing, learning and adapting every moment we're alive.

Far from being a simple 'shield', the immune system is a living memory bank, a communication web between every organ, microbe and emotion. It doesn't just decide when to fight off illnesses; it decides when not to fight, conserving energy for the long winter ahead. And while the last season of the year brings the usual culprits, namely viruses, low light and less movement, it also stirs a deeper biological shift: one shaped by our evolution, way before the mismatch between our biology and our modern lives started.

So yes, the cold air and the flurry of social gatherings matter when it comes to staying healthy. But so does our sleep, our stress levels, our diet and even our state of mind. Each acts as a signal, nudging immunity towards harmony or chaos. Winter, it turns out, isn't just 'cold and flu season'; it's the ultimate test of how well our internal and external worlds stay in sync.

SEASONAL CHANGES