In 2004, researchers published a study entitled "The Merry Christmas Coronary and the Happy New Year Heart Attack Phenomenon" in the journal Ciculation.
The authors had reviewed all official U.S. death certificates from 1979 to 2004 and found a spike in cardiac deaths on two days every year: Christmas and New Years'.
The research evaluated all sorts of possible causes, including emotional stress and alcohol consumption is another. The initial 2004 publication points to emotional stress as a possible factor. But lead author David Phillips, who has just retired as professor of sociology at the University of California at San Diego, says he wasn't convinced. He spend the next six years studying the data set further. What he found was even more startling:
"We found that every major cause of death shows a Christmas spike and a New Year's spike even after you correct for seasonal fluctuations in mortality," Phillips says.
He published a follow-up paper in 2010 --- in the somewhat lesser known journal Social Science and Medicine --- that examines why those two days of the year are so-called "risk factors." Once again, they examined all the computerized death certificates from 1979 to 2004 - which came to nearly 60 million.
They initially examined the deaths from all natural causes. Then they examined the five most common disease types separately.
For most major disease groups, there were more deaths during the Christmas and New Year's weeks, with spikes on the two holidays. One outlier was cancer. Cancer deaths declined slightly - but significantly.
Phillips concluded that emotional stress couldn't the main reason. The connection of emotional stress and, say a heart attack can be made. But connecting emotional stress as the cause of death for someone who dies after suffering Alzheimer's is a bit more difficult, he said. So, instead, Phillips thinks it's a combination of things, one of which is the behavior of patients.
"The patient may be feeling symptoms and may then say, well, I'm going to take care of this after the holiday because I have all my holiday plans and my relatives who are visiting. I'm not going to go in now, I'll go in after the holiday," Phillips says.
And when you delay seeking treatment, higher death rates follow.
Phillips says hospitals - like all employers - tend to reduce staffing on major holidays so that people can be home and celebrate with their families.
Plus, he says, the most experienced hospital staffers are likely to request Christmas and New Year's off, leaving what he calls the junior staff on hand to deal with problems. So, his theory is that staffing levels could affect how quickly patients are treated and the kind of attention they get.
In the end, Phillips sent a clear take-home message: "If you're feeling symptoms, don't wait until after the holidays. Go in now."