By Natasha Hinde

Copyright huffingtonpost

Next month our lives will be thrown into a state of flux for a few days as we set our clocks back an hour.

While it’s certainly inconvenient from a sleep and scheduling point of view, scientists are increasingly concerned about the health impact of clock changes, too.

A new study by Stanford Medicine researchers stressed there are long-term health hazards to shifting the clocks back and forth each year – and having one set time is likely better for our bodies.

We already know the collective loss of an hour of sleep when the clocks change has been linked to more heart attacks and fatal traffic accidents in the days that follow. It’s also been linked to worsened mental health.

And now, Stanford Medicine researchers estimate that having a fixed standard time could prevent some 300,000 cases of stroke per year – and could even result in 2.6 million fewer people having obesity.

How did they figure this out?

Researchers looked at three different time policies:

permanent standard time,permanent daylight saving timeand biannual shifting.

They wanted to see how it affected people’s circadian rhythms (the body’s built-in clock which regulates many physiological processes), and, in turn, their health.

The body’s circadian cycle can be impacted by daylight. Jamie Zeitzer, professor of psychiatry and behavioural sciences and senior author of the study, explained: “When you get light in the morning, it speeds up the circadian cycle. When you get light in the evening, it slows things down.

“You generally need more morning light and less evening light to keep well synchronised to a 24-hour day.”

Prof Zeitzer added that if you get light exposure “at the wrong times” it can weaken the circadian clock, which isn’t good news for our bodies. An out-of-sync circadian cycle has been associated with a range of poor health outcomes.

So, researchers used a mathematical model to translate light exposure under each different time policy (listed above), based on local sunrise and sunset times, to how much a person’s circadian cycle had to shift to keep up with said time policy.

Having a set time could cut obesity and stroke rates

Over the course of the year, most people would experience the least circadian burden under permanent standard time, which prioritises morning light, according to the study, led by Lara Weed, a graduate student in bioengineering.

Using health data from the US-based Centers for Disease Control and Prevention, their models showed that permanent standard time would lower the prevalence of obesity by 0.78% and the prevalence of stroke by 0.09%.

While this seems like a small percentage change on the face of it, when applied to the population of the US, for example, it would amount to 2.6 million fewer people with obesity and 300,000 fewer cases of stroke.

Under permanent daylight time, the nationwide prevalence of obesity would decrease by 0.51%, or 1.7 million people, and stroke by 0.04%, or 220,000 cases, the model suggested.

Prof Zeitzer said: “We found that staying in standard time or staying in daylight saving time is definitely better than switching twice a year.”

How else can I reduce my stroke risk?

If you want to make some adjustments in day-to-day life to reduce your risk of stroke, The Stroke Association recommends these lifestyle changes:

quitting smokingexercising regularly (the NHS advises at least 150 minutes of moderate intensity activity a week)sticking to the recommended alcohol limits (no more than 14 units a week)following a healthy dietstaying a healthy weight.