Why Cardiac Rhythm Issues Usually Occur In The Morning?

Numerous studies have demonstrated that people are more likely to experience potentially fatal heart rhythm abnormalities (also known as “ventricular arrhythmia”) in the morning when they wake up from a night of sleep, although the exact trigger mechanism is still unknown.

The natural spike in the stress hormone cortisol that occurs in the morning has been related to heart problems, according to study led by Imperial College London.

Researchers discovered that cortisol interacts to a particular receptor in cardiac cells in a mouse research. Once in the nucleus, the receptor affects the genes that govern the ion channels in the cell membrane, which in turn regulate heartbeats. The heart is far more susceptible when the ion channels’ activity varies because it’s simpler for the normal electrical impulses that power heartbeats to degenerate into more erratic activity, or arrhythmia.

Sleep has an impact on cortisol’s circadian, or day-night, cycle; minutes before someone wakes up, cortisol levels rise.

The possibility of novel therapies in this area is also enhanced by the link’s finding. Dr. D’Souza and associates then demonstrated that, in mice, infusion of a medication that blocks the cortisol receptor stops the ion channel alterations that occur in the morning and, consequently, the susceptibility to cardiac rhythm irregularities.

According to National Heart and Lung Institute (HNLI) lead researcher Alicia D’Souza of Imperial, “Our hearts are effectively different organs at different times of the day. They are more vulnerable first thing in the morning because of ancient circadian rhythms, which have evolved over millions of years. All species have this in common, so although our study is in mice, we believe this is directly applicable to human and mammalian hearts.”

According to Professor James Leiper, Associate Medical Director of the British Heart Foundation, “Ventricular arrhythmias can strike at any time and, if left untreated, can lead to a loss of consciousness, sudden cardiac arrest, and death. It is crucial we continue to investigate the causes of these arrhythmias so we can take action to prevent them.”

“This intriguing study in mice reveals a possible solution to the mystery of why ventricular arrhythmias are more common in the morning. Identifying a rise in cortisol as the culprit could allow us to explore new treatment options that could reduce arrhythmias in those most at risk. Further research will be necessary to establish whether these findings are also seen in humans.”

This is the most recent study in a series conducted by Dr. D’Souza and Professor Mark Boyett of the University of Bradford to investigate why the heart exhibits a significant day-night rhythm in its electrical activity and why the heart is susceptible to various arrhythmias at different times of the day or night.