The change of time raises the risk of heart attacks

The change of time raises the risk of heart attacks


Changing the schedule, delaying or advancing the clock to take advantage of the natural light of the day, can have several benefits. But apparently it’s not good for your health.

Image caption To advance one hour the clock mismatches the internal mechanism of the cells and provokes a stress response.


A new investigation in the United States found that advancing the clock one hour, a change that in the northern hemisphere countries takes place in March, is linked to an increased risk of suffering a heart attack.



Scientists at the University of Alabama, Birmingham, found a 10% greater risk of having a heart attack during the two days following the change in schedule.

On the other hand, they add, that risk is reduced by 10% when the change of schedule takes place in winter and the clock is delayed by one hour.

Although researchers do not know precisely what is the mechanism that causes this risk, they believe that changes in schedule, no matter how small, “derail” the body’s internal biological clock.

As Professor Martin Young, who led the study, explains, every cell of the organism is governed by its own molecular clock, the so-called circadian rhythm, which allows our tissues and organs to anticipate the day and night events and adjust to they.

When changes occur in this biological clock, for example work a night shift, travel through time zones and even reduce an hour of sleep to adjust the clock to daylight saving time, our cells are waiting for an event, such as one more hour of sleep , which does not happen, and this causes a stress response.

This negative response, mainly in those individuals who already have other risk factors for cardiovascular disease, can trigger an event such as a heart attack.

Cardiac rhythms

“We do not know precisely why this happens, but there are several theories,” says Professor Young.

“There are several factors, including sleep deprivation, the organism’s circadian clock and the response of the immune system, which must be taken into account when studying the reasons why advancing the clock one hour may be harmful to health.”

The researchers found that the highest risk of having a heart attack was seen on Monday and Tuesday after the schedule change, when people must get up an hour early to go to work.

“Individuals who are deprived of sleep often have higher body weight and are at higher risk of developing diabetes or heart disease,” explains Professor Young.

“Sleep deprivation can also alter other biological processes, including the inflammatory response, which can contribute to a heart attack, and a person’s reaction to sleep deprivation and time changes depends on whether that person is morning or nightlife. “Nightlife has many more difficulties in adapting to the advancement of the clock,” he adds.

There have been few studies with humans that analyze this link. However, studies carried out with mice confirm the risk of a cardiovascular event after a change in the biological clock.

In experiments with mice, Dr. Young’s team found that animals whose biological clocks had been genetically engineered showed altered responses in their immune system and this led to an increased risk of developing heart disease.

The human organism eventually adapts to the schedule changes.

But while our cells adapt to the changes, Professor Young suggests getting up 20 minutes earlier on Saturday and Sunday when the schedule changes to prepare the body to adapt to the “shock” of sleeping one hour less on Monday.

It also recommends, during that weekend, to be exposed as early as possible to the outside light of the day and, if possible, to remain active during both days.

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