Immune system has seasonal cycle

May, 2015

A study has revealed that the immune system has a seasonal cycle, in which its activity is boosted during the winter and relaxes during the summer. While the winter increase in immune defences presumably helps us stave off infections, it also raises the risk of harmful inflammation, effectively lowering the threshold for heart attacks, stroke, diabetes and even some psychiatric conditions. This may explain why deaths from conditions ranging from heart attacks to diabetes and schizophrenia increase in winter.

The study used blood samples from more than 16,000 people living in both the northern and southern hemisphere

Dopico, X. C., Evangelou, M., Ferreira, R. C., Guo, H., Pekalski, M. L., Smyth, D. J., … Todd, J. A. (2015). Widespread seasonal gene expression reveals annual differences in human immunity and physiology. Nature Communications, 6, 7000.

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