How human genes work, appears to be profoundly affected by the seasons, said scientists.
This may be the underlying cause why some ailments appear to be aggravated during winter, Nature Communications published, reports BBC.
They discovered genes tangled with immunity, the body’s defense to fight infection, were more active during the cold months.
But while this aids in the fight against viruses like flu, it could trigger or could worsen conditions, like arthritis, where the body assaults itself.
Blood and tissue samples of 16,000 individuals from around the globe were analyzed by an international research team.
22,000 genes were scrutinized and a fourth showed clear symptoms of seasonal variation.
The gene changes that picked the researcher’s interest were those involved with immunity and inflammation.
During cold season in the winter months, from December to February, people residing north of the equator, and June to August, those people from the southern hemisphere, have the most active genes.
In their study, people who live close to the equator, where high temperatures are noted year long, a different pattern was detected. Inflammation and immunity were linked to rainy season, when malaria was more rife.
But in Iceland, where for most of the time it is cold, fewer seasonal changes have been observed.