In the wake of Christmas pudding and gift-giving as families celebrate the coming new year, a curious phenomenon occurs – mortality rates spike to the highest levels of the year.
Researchers have long noted this correlation between the Christmas season and elevated death rates, but the precise reason for the increase remains shrouded in mystery.
Some studies have suggested that the cold air swirling around the holiday season may be to blame. People facing some life-threatening illnesses, such as heart disease or respiratory problems, may be more susceptible to the cold, researchers surmised.
But a new study, published in the Journal of the American Heart Association, suggests there’s more – or perhaps something entirely different – at play.
Researchers from the University of Melbourne in Australia studied the health effects of Christmastime in New Zealand, where the holiday occurs during the warm months of summer.
The research group sought to replicate “the earlier Northern Hemisphere analysis using data from New Zealand, which allows us to separate any winter effect from the holiday effect.”
The team discovered that, when controlling for the weather, mortality rates still spiked. “We found that 4.2 percent more persons die from a cardiac‐related cause outside of a hospital during the Christmas period than would be expected based on long‐term seasonal trends,” write the researchers.
“This is consistent with reports from the United States that also indicated an increased mortality rate during the Christmas holiday period in the Northern Hemisphere,” they add.
What’s more, those who die from a cardiac-related event during the Christmas season are almost a year younger on average than who die from a similar event during other parts of the year – the average age of a heart-related death during the Christmas period was 76.2 years, compared to 77.1 years the rest of the year.
The researchers also stratified the calendar dates to tease out any notable bumps in the data. They found “the effect peaking in the two weeks starting December 27,” which lands squarely within Christmas and New Year’s.
New Rationale for the Holiday Mystery
Given the warm weather in New Zealand, the researchers ruled out a number of likely causes attributable to cold weather, including respiratory disease and particulate pollution.
Instead, they believe the new study shows that other factors may be at play.
“The Christmas holiday period is a common time for travel within New Zealand, with people frequently holidaying away from their main medical facilities,” said lead author Josh Knight, a researcher at the Center for Health Policy at the University of Melbourne.
“This could contribute to delays in both seeking treatment, due to a lack of familiarity with nearby medical facilities, and due to geographic isolation from appropriate medical care in emergency situations,” added Knight.
There’s also the notion of “displacement of death,” which the researchers describe as a person’s ability to control “both hastening and postponement of death for reasons associated with the holiday period.”
“The ability of individuals to modify their date of death based on dates of significance has been both confirmed and refuted in other studies, however it remains a possible explanation for this holiday effect,” suggested Knight.
Other possible causes include increased alcohol consumption and a fatty diet, as well as heightened stress.
Richard Scott is a health care reporter focusing on health policy and public health. Richard keeps tabs on national health trends from his Philadelphia location and is an active member of the Association of Health Care Journalists.