Cold weather is a challenge in itself, with travel disruptions, snow and ice making even the simplest tasks take twice as long.

A 2021 study in the journal Medicine(opens in new tab) found that overall, U.S. cardiac arrests peak during December and January, although the exact statistics is difficult to determine.

Cold weather also causes blood vessels to narrow around extremities such as fingers and toes, a process known as vasoconstriction, Guttmann said.

Blood coagulability is also increased, said Dr. Deborah Lee(opens in new tab), a medical writer for Dr Fox Online Pharmacy in the U.K.

Another possible cause for the seasonal increase in heart attacks is vitamin D deficiency, which is more prevalent over the winter months due to a lack of sunlight.

However, more research is needed to understand the underlying mechanisms, according to a 2018 article in the journal Clinical Hypertension(opens in new tab).