For some, Christmas can be a time of stress instead of peace and goodwill – and a new Swedish study shows that 10 pm on Christmas Eve is the annual peak time for heart attack risk, particularly for the elderly and those with existing conditions.

Researchers analysed data from 283,014 heart attacks reported to Swedish hospitals between 1998 and 2013, and compared with weeks outside of holiday periods as a control measure.

In Sweden, Christmas Eve is actually the bigger event than Christmas Day, and researchers noted a 37 percent increased risk on this day, peaking at 10 pm. More generally there was a 15 percent increased risk over the Christmas period.

The risk was greatest in the over 75s and those with existing diabetes or heart disease. The study also noted more cases of heart attacks reported on Midsummer holidays, early mornings, and Mondays.

"Christmas and Midsummer holidays were associated with higher risk of myocardial infarction, particularly in older and sicker patients, suggesting a role of external triggers in vulnerable individuals," the team explains in their study.

Previous studies have also made the link between holiday seasons and more heart attacks, but this new study adds some extra interesting detail from many more years of data.

No increased risk was spotted during sporting events or during the Easter period, for example. And while there was an increased risk at New Year, it was on New Year's Day rather than New Year's Eve – perhaps because too much partying the night before was leading to symptoms being ignored or misunderstood.

While this study on its own isn't enough to prove cause and effect between Christmas and heart attack risk – unmeasured factors might be lurking unseen in the background, as with all observational studies like this – it does fit in well with the existing research out there.

Anger, anxiety, sadness, grief and stress have all been linked to heart attack risk in the past, and while we hope your Christmas is filled with joy and hope, these emotions can also come into play over the holiday season.

"Excessive food intake, alcohol, long distance travelling may also increase the risk of heart attack," one of the team, David Erlinge from Lund University in Sweden, told ScienceAlert.

"Interestingly, the pattern of increased risk in the morning which dominates the rest of the year was reversed at Christmas, with an increased risk in the evening, indicating that the stress and eating during the day triggered the heart attacks."

An earlier study from the same team linked increased heart attack risk with cold and cloudy weather, too. Considering the control data in this new study was taken from the weeks close to Christmas, this factor should already be accounted for.

The aim of the study is not to scare you away from indulging in the holiday festivities, but to look out for people who might be at risk and to try and cut down on the number of heart attacks seen over Christmas and New Year.

Erlinge told ScienceAlert that people should be aware of how emotional distress and eating way too much could increase risk – and of course to take good care of friends and family over the holiday season.

"These findings warrant further research to identify the mechanisms behind this phenomenon," conclude the researchers.

"Understanding what factors, activities, and emotions precede these myocardial infarctions and how they differ from myocardial infarctions experienced on other days could help develop a strategy to manage and reduce the number of these events."

The findings have been published in the BMJ.