Winter blues and flus

There are more than 200 viruses that can cause the common cold. As the saying goes, "coughs and sneezes spread diseases" (well, colds do anyway), although cold viruses are most commonly caught by putting your hand to your mouth after touching something (such as a door handle) with germs on it.

Nobody knows exactly why colds are more common in the winter but one theory is that the cold weather reduces blood flow to the nose, so there are fewer immune cells to fight infection.

Being stressed is thought to make you more likely to succumb. Stressed people have higher levels of steroid hormones in their blood, which is known to weaken the body's ability to fight infection.