Winter comes ... and with it, piles of colds, flus and other diseases that push us to want to stay under the comforter. But why is our body less inclined to resist disease in winter?

Several reasons explain the recrudescence of winter diseases

A priori, nothing to do with sweaters not hot enough! Indeed, several reasons would come to explain the recrudescence of the winter diseases. In the first place: the variation of our DNA according to the seasons. A recent study revealed that a quarter of our DNA changes in function of seasonality. During the winter months, according to this study, our body lowers the levels of genes related to "inflammation", the same ones that would allow us to protect ourselves against colds and flu. Conversely, in summer, it is genes that regulate our blood sugar levels that would be boosted (an explanation of why we are less hungry when it's hot?).

Other parts of the body are also changing: the immune system that is there to ward off infections is also changing. Researchers have scrutinized data from different DNA studies to compile information on about 1,000 people living in six different countries: Australia, Germany, United States, United Kingdom, Iceland, and The Gambia. , a small country in West Africa between Senegal and Guinea-Bissau. These studies have shown that the sun has a direct influence on genes that themselves have a direct influence on our resistance to disease.

Cold, vector of diseases?

Other studies have shown the incidence of cold on the recrudescence of certain viruses, and just as wanting to stay confined increased the transmission of diseases. Unventilated indoor air would make the spread of colds more obvious. A 2011 study of overcrowded dormitories in Chinese colleges proved that confinement is a vector of disease.

Finally, according to the American Health Institute, cold temperatures would allow viruses to resist better: the outer shell of influenza virus particles are more robust and survive longer when it is cold. As well as bacteria responsible for colds that are more "effective" at low temperatures.

So, you have to find something to wrap yourself up with this winter to make a barrier against these bad microbes before leaving your home: a good opportunity to have an afternoon shopping, right?