Healthy living

Moving clocks forward poses risk to health

Moving the clocks forward health risk Affects internal body clock

Planning on leaping out of bed with a spring in your step come Monday morning – after all, the clocks go forward an hour this weekend for British Summer Time?

Think again. According to new research the switch to so-called daylight saving time could seriously damage your health.

Experts say the move is linked with a ten per cent leap in the risk of having a heart attack come Monday or Tuesday morning.

Professor Martin Young, of the cardiovascular disease department at the University of Alabama, said the body’s response to a change in its ‘circadian rhythms’ may be to blame for the increased risk.

“The Monday and Tuesday after moving the clocks ahead one hour in March is associated with a ten percent increase in the risk of having a heart attack," he confirms. "The opposite is true when falling back in October. This risk decreases by about ten percent."

Although clocks move back on a Sunday morning – this year on 25 March – the rate of heart attacks doesn’t peak then because most people have a lie-in and it “doesn’t require an abrupt schedule change”.

But on Monday and Tuesday, when people tend rise earlier to go to work, heart attack risk peaks.

“Exactly why this happens is not known but there are several theories: sleep deprivation, the body's circadian clock and immune responses all can come into play when considering reasons that changing the time by an hour can be detrimental to someone's health," Prof Young said.

Unsurprisingly, night owls are most likely to have difficulty with the clocks going back. And if you are a night owl and already sleep deprived, ill effects are more likely.

Prof Young said messing about with our circadian clock is also detrimental because: “Every cell in the body has its own clock that allows it to anticipate when something is going to happen and prepare for it. When there is a shift in one's environment, such as springing forward, it takes a while for the cells to readjust.

“It's comparable to knowing that you have a meeting at 2pm and having time to prepare your presentation instead of being told at the last minute and not being able to prepare. The internal clocks in each cell can prepare it for stress or a stimulus.

“When time moves forward, cell clocks are anticipating another hour to sleep that they won't get, and the negative impact of the stress worsens; it has a much more detrimental effect on the body."

Meanwhile tests on mice showed that those who were exposed to a situation that mimicked daylight saving time and then given a dose of a drug that challenged their immune system were more likely to die than mice given the same dose but who were not exposed to any other changes.

But if all this makes you feel like pulling the duvet over your head come Monday morning and staying there till winter, Prof Young advises some steps to help your body phase into the time change in a more gentle manner.

They include waking up 30 minutes earlier than you need to on Saturday and Sunday, going outside in the sunlight in the early morning and exercising in the mornings over the weekend (as long as you don’t have pre-existing heart disease).

"Doing all of this will help reset both the central, or master, clock in the brain that reacts to changes in light/dark cycles, and the peripheral clocks - the ones everywhere else including the one in the heart - that react to food intake and physical activity,” said Prof Young.

“This will enable your body to naturally synch with the change in the environment, which may lessen your chance of adverse health issues on Monday."

This article was published on Fri 23 March 2012

Image © Galina Barskaya -

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