Did you know that most serious heart attacks happen on Mondays? Here’s why

A study by doctors in Ireland showed that serious heart attacks are more likely to happen at the start of the working week than at any other time.

ByChetana Belagere

Published Nov 24, 2023 | 9:00 AM Updated Nov 24, 2023 | 2:29 PM

Representational image of heart attack

Did you know that serious heart attacks, specifically ST-segment elevation myocardial infarctions (STEMIs), happen mostly on Mondays? STEMI is a severe type of heart attack occurring when a major coronary artery is completely blocked​​.

A study by doctors at the Belfast Health and Social Care Trust and the Royal College of Surgeons in Ireland — and presented at the British Cardiovascular Society Conference in Manchester — showed that serious heart attacks are more likely to happen at the start of the working week than at any other time.

What’s interesting is cardiologists South First spoke to also say that they have seen this phenomenon across India, too.

Speaking to South First, renowned intensive cardiologist Dr Deepak Krishnamurthy of Sakra World Hospital in Bengaluru, says, “It is well known amongst cardiologists that there are certain times when more people are likely to get heart attacks — on Mondays, early mornings, and winters.”

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Blue Monday! What is it?

As part of the study, the researchers examined data from 10,528 patients across Ireland, including both the Republic of Ireland and Northern Ireland, who were admitted to hospitals between 2013 and 2018 for STEMI.

STEMI heart attacks were found to spike at the start of the working week, with the highest rates occurring on Mondays. In an official news release by the British Cardiovascular Society, serious heart attacks are more likely to happen at the start of the working week than at any other time.

The release said that scientists have so far been unable to fully explain why this “Blue Monday” phenomenon occurs. Previous studies suggesting that heart attacks are more likely to happen on a Monday have highlighted an association with circadian rhythm — the body’s sleep or wake cycle.

Cardiologist Dr Jack Laffan, who led the research at the Belfast Health and Social Care Trust, said in the official release, “We’ve found a strong statistical correlation between the start of the working week and the incidence of STEMI. This has been described before but remains a curiosity. The cause is likely multifactorial, however, based on what we know from previous studies, it is reasonable to presume a circadian element.”

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Increased heart attacks on Mondays

Dr Laffan noted that the most likely time for a cardiovascular event is in the early morning hours — between 6 am and 10 am — when cortisol and other hormones rise as people wake up. These hormones also increase under stress, which might explain the higher incidence of heart attacks on Mondays due to the stress of returning to work after the weekend​​​​.

This phenomenon, also observed on Sundays but to a lesser extent, is attributed to the body’s circadian rhythm, which governs sleep and wake cycles.

Click to enlarge.

Click to enlarge.

The phenomenon of higher heart attack rates on Mondays is not unique to Ireland. A 2005 review of 28 studies covering 16 countries and more than 1.6 million cardiac events also found a higher incidence of heart attacks on Mondays.

Confirming the phenomenon to South First, Dr Madan Mohan, renowned cardiologist at MGM Healthcare in Chennai, says, “This phenomenon also occurs here. The relaxation experienced by the heart on a Sunday, when followed by an adrenaline surge due to work-related stress on Monday, can lead to complications. This is particularly prevalent among individuals with pre-existing, yet undiagnosed, heart conditions.”

The “Blue Monday” effect might be associated with factors like alcohol consumption too, adds Dr Krishnamurthy.

He explains, “Weekend binge alcohol consumption and partying, sudden exposure to polluted air after a weekend of being indoors, disturbed sleep patterns on weekends, and so on, are some reasons that could result in Monday heart attacks.”

Doctors agree that the body’s response to stress is known to increase the risk of high blood pressure, heart attacks, and strokes​​.

Also read: Importance of Primary PTCA for acute myocardial infarction

Why is this research important?

Doctors say that this research will help in understanding the timing and causes of severe heart attacks.

However, cardiologists says that further investigation is needed to unravel the specifics behind the increased risk on certain days of the week, which could help doctors better understand and potentially prevent these deadly events.​

Professor Sir Nilesh Samani, Medical Director at the British Heart Foundation (BHF), says in the release, “This study adds to evidence around the timing of particularly serious heart attacks, but we now need to unpick what it is about certain days of the week that makes them more likely. Doing so could help doctors better understand this deadly condition so we can save more lives in future.”

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Why more heart attacks in winters, early mornings?

Dr P Kamat, Professor and Head of Cardiology at KMC Hospital in Mangaluru and founder of Cardiology at Doorstep, says, “Early morning periodicity is known and also winter predilection is a known one.”

Doctors said that heart attacks are more common early in the morning due to a mix of biological factors. The body’s circadian rhythm causes a surge in stress hormones like cortisol and adrenaline, leading to increased blood pressure and heart rate.

Additionally, blood pressure naturally peaks in the morning and blood tends to be more concentrated and viscous, raising the risk of clot formation.

The endothelium or inner lining of blood vessels may also function less efficiently, increasing the likelihood of plaque rupture. Also, there is often reduced heart rate variability during these hours, a condition linked to heightened heart attack risk.