- - The Effects of Day Light Saving Time's "Fall Back " Can Have on Your Health

The Effects of Day Light Saving Time’s “Fall Back ” Can Have on Your Health

Daylight Saving Time officially ends at 2:00 am on the first Sunday in November. In theory, “falling back” means an extra hour of sleep this weekend

Winston Churchill once described Daylight Saving Time like this: “An extra yawn one morning in the springtime, an extra snooze one night in the autumn… We borrow an hour one night in April; we pay it back with golden interest five months later.”

That’s an overly optimistic view. In reality, many people don’t, or can’t, take advantage of this weekend’s extra hour of sleep. And the resulting shift in the body’s daily sleep-wake cycle can disrupt sleep for several days.

Research teams around the world have tried to determine if losing or gaining an hour of sleep because of Daylight Saving Time make a difference in health. Michigan researchers, writing in the American Journal of Cardiology, showed a small increase in heart attacks on the first day (Sunday) of the spring transition to Daylight Saving Time, when we “lose” an hour of sleep. This echoed a Swedish study published in the New England Journal of Medicine showing a small increase in heart attacks after the start of Daylight Saving Time and a small decrease at its end.

Other researchers have looked at driving accidents, workplace safety, and even school performance, with mixed results.

Daylight Saving Time and sleep

The focus on gaining or losing an hour of sleep overlooks the bigger picture—the effect of Daylight Saving Time transitions on the sleep cycle. An excellent review in the journal Sleep Medicine Reviews by Dr. Yvonne Harrison, a senior lecturer at Liverpool John Moores University in England, concludes that a seemingly small one-hour shift in the sleep cycle can affect sleep for up to a week.

In the Fall, only a minority of people actually get that promised extra hour of sleep. During the following week, many people wake up earlier, have more trouble falling asleep, and are more likely to wake up during the night. People who tend to be so-called short sleepers, logging under 7.5 hours a night, and early risers (also known as larks), have the most trouble adjusting to the new schedule.

Similar problems are seen in the Spring. Again, the adjustment is harder for larks and short sleepers.

Springing back

Each of us experiences predictable physical, mental, and behavioral changes during the course of a day. These are called circadian rhythms. The daily cycle of light and dark keep them on a 24-hour cycle.

Sleep is a component of circadian rhythms. It is affected by outside influences, like light or Daylight Saving time. It can also affect the body’s other rhythms.

It’s difficult to side-step the effects of Daylight Saving time on sleep. Experts advise that individuals should be aware that it can take your circadian and sleep rhythms a week or so to get adjusted to the new clock. Regular exercise, preferably at the same time each day, may help get your sleep cycle back on track. Going to bed and getting up on a schedule can help. And giving in to brief afternoon nap or two during the week may be a pleasant and relaxing way to restore lost sleep.

When did Daylight Saving Time Begin? 

It all starts with Benjamin Franklin in 1784. During his time as the ambassador to France, Franklin wrote a lighthearted letter to The Journal of Paris, wherein he satirically complained of being woken up too early by the bright morning sun. In the essay he suggests Parisians change their sleep schedules to wake up at dawn, enabling them to save “by the economy of using sunshine instead of candles.”

However, Franklins was meant to be humorous, and merely suggested changing the Parisian’s sleep schedule – not switching clocks forward.

Over a century later, in 1907, an English builder and horseman William Willett published a pamphlet advocating moving the clocks forward 20 minutes a week for a period of 4 weeks in April. He wanted to grant people like himself more opportunities for daytime recreation and costs savings in electrical lighting. Even though he had champions like Winston Churchill by his side, Willett died in 1915 and never saw Parliament pass his idea.

It took the hardships of war for DST to finally pass. During World War I, countries needed coal to support the war efforts, but rations were running slim. In 1916, Germany became the first country to implement DST, with others like Britain following suit soon after.

Despite the common myth, farmers had nothing to do with the founding of DST. In fact, they heavily opposed it, leading to its repeal in 1919 after the war was over. DST is actually very disruptive to farmers, since their schedules already follow the sun. With DST in place, their workday was delayed by an hour, as they had to wait longer for morning dew to evaporate from their hay. It was cut short on the other end, too, since employees continued to leave at the same time for dinner.

Since the 1919 repeal of national DST in the U.S., the time change has been regulated at a state and local level. Any changes to the practice are usually dictated by commercial interests (not farming ones).

Interesting Facts about Daylight Saving Time

Daylight Saving Time certainly has an interesting history, but the fun facts don’t stop there. Here are a few more trivia-worthy tidbits about this practice.

It’s reversed the birth order of twins

In November 2016, right after “Fall Back,” a pair of twin boys were born on either side of the time change. One boy was born at 1:39am and the other at 2:10am, or rather, 1:10 am. The second twin was younger by 31 minutes, but since his date of birth was recorded after the time change, his birth certificate says he’s 29 minutes older!

Halloween used to be much darker

The end of Daylight Saving Time didn’t always take place in November in the U.S. It used to take place earlier, making Halloween a suddenly very dark night—which made parents nervous about their children’s safety, and candy makers very nervous about their sales.

In the 1980s, the National Confectors Association lobbied, along with golf and barbeque industries, to push the end of DST back a week into November. Their dreams weren’t answered until 2007, when President George W. Bush extended daylight saving time as part of the Energy Policy Act.

It makes bartending interesting

In many large cities, it’s common for bars to stay open until 2am. In the fall, this coincides with Fall Back. While the bar can decide whether or not they want to close at the “normal” time or not, many decide to stay open, effectively giving partygoers an extra hour out on the town.

In the spring, partiers may be unhappy to hear, that means bars technically close one hour early, since the clock says 2am at 1am. Stay open later, and the bar could risk an after-hours service violation.

Not everyone uses the 1-hour standard

The vast majority of countries participating in DST shift their time by 1 hour. But in one place in the world, time only shifts by 30 minutes. From April to October, residents of Lord Howe Island off the east coast of Australia are 30 minutes ahead of their time zone counterparts.

Who uses Daylight Saving Time?

Currently, less than 40% of countries participate in DST, a number which includes countries in both the Northern and Southern hemispheres. DST begins for Northern Hemisphere countries in the spring, between March and April, and ends in the fall, between September to November.

Because summer occurs at the opposite time of year for Southern Hemisphere countries, they practice DST between September to November and March to April. Countries around the equator do not participate in DST, since their amount of sunlight stays relatively stable throughout the year.

The number of countries participating in DST continues to fluctuate. Some countries observe DST sporadically. One such example is Libya, who used it continuously from 1982 to 1989, then again in 1997 and 2013. Chile delayed the start date of DST twice, for a 1987 Pope visit and a 1990 presidential inauguration.

Some countries have given up DST completely. A few of the major countries who no longer participate in DST include Japan, India, and China.

In fact, not even all parts of a country may participate in DST. In the U.S., Hawaii and Arizona do not observe DST, and some Canadian provinces do not observe it. Today around 70 countries use DST in at least some part of their country.

Other benefits and drawbacks of Daylight Saving Time

Some countries continue to participate in DST because they believe the extra daylight is beneficial to society, perhaps resulting in fewer traffic accidents and more opportunity for outdoor exercise. Other countries don’t believe the tradeoff is worth it, considering the disruptions DST causes to a 24-hour, global economy, and growing research indicating an increase in workplace injuries and heart attacks in the first week following the spring time change.

To date the research suggests some clear benefits to DST, some clear disadvantages, as well as some inconclusive evidence as to whether DST has a positive, negative, or neutral effect on some things.

More daylight

One of the biggest arguments for DST is that we get more daylight in the evening. In theory, this gives us more time to spend outdoors with recreational activities like exercise, reduces the risk for car accidents since there are less people driving when it gets dark, and lessens our reliance on indoor lighting.

Energy conservation

This last point gets to the main reasons proponents give for sticking to DST: energy conservation. DST went into place during WWI, to reduce the burden on coal production. With more daylight, the theory goes, we need less energy resources. A U.S. Department of Transportation study from 2008 found that the total electricity savings are about 0.5% during each day of DST, which equates to a .03% reduction averaged over the course of the year.

Although, more recent studies suggest DST does the opposite; it may increase energy consumption. In 2008, Indiana researchers analyzed the effect on energy consumption during DST. In contrast to popular belief, they found that residential electricity demand actually increases during DST by 1%. While we might expect to save money on lighting since we have an extra hour of natural sunlight, in reality those costs seem to be offset by an increase in heating and air conditioning during the time people spend inside.

Add to all this the fact that today’s light bulbs are much more energy-efficient, so lighting is less of a drain on our total energy consumption than it was when DST first began.

Reduced crime

Putting the energy issue aside, there are other, unintended benefits to DST. Crime tends to occur more during the nighttime hours, and one 2015 study found that the daily robbery rate drops 7% following the beginning of DST in the spring, thanks to the sudden increase in daylight evening hours.

How were the study authors able to definitively attribute this to DST? The overall rate dropped overall by 7% but it dropped 27% during the hour that suddenly had sunlight.

Economic impact

One issue with DST is the lack of coordination among countries worldwide, despite their participation in a global economy. As we reviewed above, countries practice DST to varying extents (or not at all) at different times during the year. This makes it difficult to communicate globally, especially in the immediate days following a time change.

One 2011 study found a “surprisingly strong” negative relationship between DST and SAT scores. Using the estimate that a 1 point reduction in SAT scores is associated with a 1.5% difference in annual earnings, the researchers extrapolated the yearly economic impact could be as high as a $1.29 billion loss for a state like Indiana.

Lack of public enthusiasm

Only 55% of people don’t mind DST. The other 45% either find it somewhat or majorly disruptive to their lives. The arbitrary time change feels disruptive, and people get bummed about leaving for work in the darkness, or heading home in the darkness when it was previously light out.

Driving accidents

A few studies have been done regarding the relationship between DST and a rise or fall in traffic accidents. Thus far, the results are conflicting.

One 2001 study attributed a “small increase” in fatal accidents the Monday following DST to the resulting sleep deprivation from Spring Forward. Meanwhile, a 2010 study found that the increase in car crashes the day following DST was “not statistically significant,” and that overall DST led to fewer crashes due to improved visibility. Yet another study from 2010 found that DST had no impact on traffic accidents, positive or negative.

Finally, DST has a negative impact on your sleep, which trickles down to other health aspects of your life. We’ll review these in the following section.

Does Daylight Saving Time affect sleep?

Even in instances where we don’t realize it, the effect DST has on our sleep is significant and negative.

DST and sleep deprivation

A 2013 study published in Sleep Medicine found that while people generally believe they adjust to the new schedule quickly, it takes them at least a week to do so. During that time, they’ll experience fragmented sleep and an overall sleep loss that results in sleep deprivation during the spring change.

Perhaps more surprisingly, these negative effects to sleep persist during the fall time change, when people popularly believe they enjoy an extra hour of sleep. The same study found that people generally do not get extra sleep on that first night. Further, they continue to wake up earlier than their clocks would have them do so over the next five days, resulting in a net loss of sleep for the week.

The study authors found that the sleep deprivation in the week following both the beginning and end of DST indirectly led to higher rates of traffic accidents, and a disruption to bodily functions that shouldn’t be ignored.

What will happen with Daylight Saving Time in the future?

The number of countries practicing DST continues to change. Each year bills get proposed to adjust or change DST. Sometimes they get passed, and sometimes they don’t.

Here at Tuck, we don’t take sides in the ongoing debate for and against DST, but there are definitely some interesting things happening in the world revolving around this practice.

Here’s some of the latest news and legislation happening around DST.

In the United States:

In 2018, Florida passed the Sunshine Protection Act. This act would exempt Florida from the federal 1966 Uniform Time Act and transition Florida to adopt DST year-round—meaning that for half of the year, it would be 4 hours ahead of its counterpart on the West Coast.

The Uniform Time Act gives states the option to either adopt DST or to remain on standard time all year (as Arizona does). To switch to year-round DST, this Act needs to change. While the bill was approved in the Florida state Senate and House, it still needs to be approved by Congress. Until that happens, Florida will continue to practice DST like the rest of the states.

Similarly, in California, residents voted to approve Proposition 7 on the midterm ballot by nearly 60%. Because California had adopted DST through Proposition 12 in 1949, it needed to be repealed by voters before state legislature could take action toward changing DST in the state. Prop 7 repealed Prop 12, paving the way for California to move to year-round DST—once Congress modifies the Uniform Time Act.

Other states currently seeking exemptions from the federal Uniform Time act include Montana, Texas, and Nebraska.

In Europe:

When the European Union surveyed 4.6 million of its residents, they found 84% disliked seasonal time changes. Beginning at the end of October 2019 (or the end of DST in 2019), EU member countries could determine whether they want to move permanently to DST or stay on standard time.


he value of DST remains a heated debate. Clear benefits are the increase in evening daylight and resulting decrease in robbery crimes. However, DST does have negative impacts on our sleep and the economy. As for the effect of DST on energy consumption and traffic accidents, the evidence remains mixed.

Whichever side of the DST debate you’re on, it does appear that one side is winning out over the other, as more countries continue to drop DST in favor of a single time schedule year-round.

If you live somewhere that observes DST, the best thing you can do to minimize the impact to your sleep and your overall health is to prepare. Just like you might do to avoid jet lag, start gradually shifting your schedule to get used to the time change before it actually happens. Then, once it’s here, you’ll be a lot less tired and out of sorts than the rest of your friends.


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