Our immune systems vary with the seasons, according to a study led by Professor John Todd and Drs Xaq Castro, Chris Wallace and Marina Evangelou that could help explain why certain diseases are aggravated in winter whilst people tend to be healthier in the summer.

The study, published in Nature Communications, shows that the activity of almost a quarter of our genes (5,136 out of 22,822 genes tested) differs according to the time of year, with some more active in winter and others in summer.

This seasonality also affects our immune cells and the composition of our blood and adipose tissue.

It’s been known for some time that various diseases, including cardiovascular disease, type 1 diabetes, multiple sclerosis and psychiatric disorders display seasonal variation, but it’s now evident that part of the explanation could be periodicity of our physiology.