The risk of suffering a heart attack peaks at around 10pm on Christmas Eve, most likely because of increased emotional stress, a new study suggests.

Previous research has found that heart attacks peak throughout the western world over the Chirstmas and New Year period. An increased risk is also associated with other short-term events linked to emotional stress, such as major sporting events and stock market crashes.

However, the data on exact timings is limited, so Swedish researchers decided to examine this further. They analysed the exact timing of over 283,000 heart attacks that had been reported in Sweden over a 16-year period.

They considered the two weeks before and after a holiday - and the same period the year before and after a sports event - as the control periods.

The study found that Christmas and midsummer holidays were associated with a higher risk of heart attack (15% and 12% respectively) when compared with the control period. Early mornings (8 am) and Mondays were also associated with a higher risk.

However, the study also found that by far, the highest risk of suffering a heart attack was associated with Christmas Eve - with a 37% increased risk. This peaked at around 10pm.

The risk was greatest among those aged over 75, as well as those with heart disease and diabetes.

Meanwhile, the study found no increased risk on New Year's Eve. There was an increased risk on New Year's Day, although the researchers suggested that this was ‘possibly explained by a negligence and masking of symptoms due to alcohol'.

Unlike previous studies, this particular one did not find any increased risk during the Easter period or during sporting events.

The researchers acknowledged that this is an observational study, so no firm conclusions about cause and effect can be drawn. However, they emphasised that anxiety, sadness, anger, grief and stress have all been found to increase the risk of a heart attack, and people are more likely to experience these heightened emotions during holiday periods, such as Christmas.

Details of these finding are published in the British Medical Journal.