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Updated: July 25, 2022
By Jordan P. Roberts, PA-C

Health Effects of Daylight Saving Time

Brain Health and Daylight Saving Time Modern MedEd

Is daylight saving time worth the increased incidence of stroke, heart attack & motor vehicle collision? How about annual $275 million cost

The Dark Side of Daylight Saving Time

Like most normal people, you probably think of daylight saving time (DST) twice a year. And like most normal people, you probably really only want to know two things.

  1. Which way do the clocks go? (Am I going to be early or late tomorrow?)
  2. Is there an apostrophe -s after ‘saving’?

Let's get number one out of the way first. If you were raised by wolves (or in Arizona), you may have trouble remembering. In the spring, you spring forward an hour. In the fall, you fall back an hour. As for your second question; there is no apostrophe -s. It's daylight saving time. Now you can be insufferable at parties, too.  

You probably don’t worry about getting slammed with medical emergencies when you return to work afterwards. Will you lose more than just an hour of sleep because of an increase in acute myocardial infarctions, ischemic strokes, and pedestrian-involved road traffic incidents after setting the clocks forward? And what are your chances of getting that sleep back in November when DST ends?

Like any major public health policy, this one has unintended benefits, unforeseen downsides, and countless confounding factors that influence its perception. 

This article will focus on the medical risks, public health side effects, and economic outcomes associated with springing forward to daylight saving time.

Why Do We Have Daylight Saving Time?

Some form or another has probably been around since before clocks were invented. However, the modern-day version exists because of small tweaks here and there every few decades. It lasts from early March to early November in the United States (except Arizona and Hawaii), which is almost two thirds of the year. It's always been controversial, but now it's cool to dislike it.

An extra hour of daylight would allegedly have far-reaching benefits to the country. It would promote individual health, national energy conservation, and the backbone of the economy, small (and let's be honest, large) business.

Physical health would get a boost from the extra hour of sunlight people had to play outdoors after work or school. Mental health would be bolstered by more sunlight, to the chagrin of dermatologists everywhere. Road traffic accidents would be nearly non-existent. Knowing that trauma is the leading cause of death in the 1 to 49 years old age group, this should automatically pay for itself, right?

Daylight saving time was more than improving health. It was also about improving economic activity. More people out walking during daylight hours around means more people out buying stuff, according to that logic.

So daylight saving time began as a way to conserve energy, promote health, and strengthen the economy, but how well is that going?

Let's look at the physical and mental health effects, as well as the economic impact daylight saving time has had, starting with psychological health. 

Disturbing Effects on Psychological Health

Losing an hour of sleep is a big deal for anyone. Ask a toddler and a medical profession how their day is going when they didn’t get their nap and you’ll get the same response.

Lack of sleep can worsen motor function and task performance, and has been recently tied to an increased risk of certain types of dementia. But an Australian study took it a step further, and found a slight increase in the number of males committing suicide in the weeks after daylight saving started.

Minus one point for psychological health.

Negative Effects on Physical Health

Strokes, Heart Attacks, and Trauma

In the springtime, the risk of ischemic stroke appears to increase somewhat for a couple of days following the transition to daylight saving time. The effect is short-lived, but not if you are the one with a stroke. The reason why this happens is unclear; remember that correlation is not causation. 

The Monday after the jump, the relative risk of acute myocardial infarction (AMI) also increases. However, some authors dismiss this by pointing out the decrease in AMI that occurs in the autumn transition out of daylight saving time makes this a zero-sum finding.

These authors may or may not be interventional cardiologists wondering when the net increase in business kicks in for them. Again, the underlying cause of this phenomenon (if it truly exists) is not clear from these data.

With the sun up later, you’d think the roads would be safer and fewer collisions would occur.  However, anyone who's ever worked in a trauma center knows that summertime is synonymous with trauma. When you account for the restricted sleep and mix that with high velocity missiles (automobiles), it makes more sense.

Fatal motor vehicle collisions increase for a full two weeks after the spring transition. Most, unfortunately, involve pedestrians and happen around sunset. So much for going on that evening run or strolling by the shops.

The Surprisingly High Cost

Even if you survive your AMI and your stroke symptoms resolve within twenty-four hours, you cannot escape the economic effects. According to a paper published in the redundantly named American Economic Journal: Applied Economics (really), shifting the time of day in reference to the sun only shifts the distribution of injuries and fatalities around.

However, the increased sleep deprivation leading to additional motor vehicle collisions, injuries, and reduced performance at work clock in around $275 million per year. There are also real economic benefits to some industries, but at a potential cost of an additional thirty deaths per year. The infographic below might do a better job of summarizing this. Check it out and let us know what you think.

If you are trying to control your own economic output, be sure to try to convince your employer to give you an unlimited continuing medical education (CME) allowance.

Or try one of these great CME options for primary care, pediatrics, or urgent care practitioners that won't cost anywhere near $275 million a year.

What To Do About It

Aside from lobby for the end of this absurd practice, not much. Except be ready and anticipate these effects. Make sure you are up to date on post-DST medical and neurological conditions.

Also be thankful that all this doom and gloom does reverse when DST ends in November. So is it worth having it or is the controversy still alive?

If you enjoyed this article, check out the free infographic below. 



First Published: March 11, 2018

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