12 Surprising Effects of Daylight Saving Time

bee32/iStock via Getty Images
bee32/iStock via Getty Images

Every March, clocks "spring forward" across much of the United States, robbing people of one precious hour of sleep. In November, those same clocks "fall back," giving them 60 extra minutes of shut-eye. While hearing people complain about missed alarm clocks is one not-so-surprising effect of Daylight Saving Time, the possibility of a longer prison sentence for those going before a judge on "sleepy Monday" is less expected. Here are 12 surprising effects of Daylight Saving Time—the good, the bad, and the scientifically ambiguous.

1. Increased Spending

Woman whips out her credit card while hanging out on a hammock
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In 2016, JP Morgan Chase decided to look into the economic consequences of Daylight Saving Time (DST) by examining Los Angeles and Phoenix, two cities that are large, relatively close to each other, and have stable weather. Critically, Phoenix doesn't observe DST while Los Angeles does [PDF].

Among their findings, DST was "associated with a 0.9 percent increase in daily card spending per capita in Los Angeles at the beginning of DST." Perhaps more surprising, the end of DST was associated with a per capita daily spending reduction of 3.9 percent.

2. A Higher Risk of Heart Attacks

An image of a man grabbing his chest.
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Many studies have shown that DST is associated with an increase in heart attacks, with one study showing a 24 percent increase in the number of heart attacks on the Monday after DST at a group of Michigan hospitals. According to the University of Michigan, Mondays are bad for heart attacks in general (researchers believes the stress of beginning a new workweek and changes to the sleep-wake cycle are the reason why), but DST makes everything worse. Interestingly, the Tuesday following the end of DST was associated with a 21 percent drop in patients.

3. Missed Appointments

Young man runs to catch a missed train
iStock.com/Drazen_

Somewhat relatedly, a 2017 study found that the percentage of missed medical appointments increased significantly following DST. But as with heart attack risk, the missed appointments decreased in the fall—at least temporarily.

4. More Car Accidents … Maybe (at Least for a Few Days)

An image of a car with a broken headline after being in an accident.
iStock.com/CHRISsadowski

Another field where studies aren't as consistent as one might expect is traffic accidents. In 2001, an American study found that there was a significant increase in accidents on the Monday after the shift to DST. A 2018 New Zealand study echoed the sentiment, finding that on the first day of DST road accidents increased 16 percent. In contrast, a Swedish study found that DST didn't have any important effect in that country.

Of course, there's more to DST than just those first couple days. After DST has gotten started, there's more light on the road later in the day. Several studies have found this light reduces accidents substantially, so much so that one study concluded that a year-round DST would reduce motor vehicle occupant fatalities by 195 per year.

It's so complicated that a 2010 analysis in Minnesota listed 10 studies that found positive effects of DST on road safety, and six studies that showed negative effects in both the spring and fall changes.

5. Longer Prison Sentences

A photo of a judge handing out a sentence with a clock sitting next to her
ISTOCK.COM/TZAHIV

Researchers frequently use DST to study sleep deprivation in populations, as it's a period of time when we all wake up an hour before we’re used to. One of these studies focused specifically on judicial punishment in U.S. federal courts. The researchers looked at "sleepy Monday" (the Monday after the time change) and compared the sentence lengths to other Mondays. They found that on "sleepy Monday," judges handed out 5 percent longer sentences. But don't think you can get a lighter sentence during the fall switch; the researchers found no effect on sentencing at that time. But the researchers point out that this probably isn't limited to judges—even managers may find themselves in the mood for doling out harsher punishments.

6. More Mining Injuries

An image of mining helmets on a shelf.
iStock.com/dannyfroese

According to one study of mining injuries from 1983 to 2006, the Monday directly after the switch to DST was associated with 5.7 percent more workplace injuries and 68 percent more workdays lost because of injuries, indicating that there are more injuries that are more severe after the switch [PDF]. There isn't, however, a corresponding decrease in the fall.

7. Fewer Koala Collisions

A street sign warns of koala bears
iStock.com/hidesy

One study decided to look at how DST affected human-wildlife interaction, specifically koala-vehicle collisions [PDF]. Because koalas are largely nocturnal, they often cross the road in the evening or at night. By shifting traffic patterns to times when it wasn't dark, the researchers found that DST could "decrease collisions with koalas by 8 percent on weekdays and 11 percent at weekends" (although the difference between weekend and weekdays wasn't significant, the researchers proposed that a slight increase in morning collisions lessened the benefit during the weekday). The researchers hope that further study can be done on human-animal interactions and DST.

Koalas aren't the only ones crossing a road that benefit from DST; pedestrians might be safer as well. One study found "no significant detrimental effect on automobile crashes in the short run" and in the long run was associated with "a 8 to 11 percent fall in crashes involving pedestrians … in the weeks after the spring shift to DST." Meanwhile, another study found that a year-long DST would mean 171 fewer pedestrian fatalities a year.

8. Decreased Satisfaction With Life in General (and Increased Use of the Word Tired)

A woman sitting in front of a computer looking tired.
istock.com/PeopleImages

In both the UK and Germany, studies have shown that life satisfaction deteriorates in the first week after the switch to DST in the spring. One study even quantified the deterioration in Germany with money. For the entire sample, the cost was calculated to be €213 (about $262), but for people in full employment—with relatively inflexible schedules—that increases to €332 ($408). And for the men in the sample, the cost of transition was €396 ($487).

Meanwhile, a Facebook analysis looked at the "feelings" people were sharing on the platform. On the Monday after the start of DST, the use of the word tired increased by 25 percent, with similar increases for "sleepy" and "exhausted" (as well as "wonderful" and "great"). In just the period from 5 a.m. to 12 p.m. on Monday, "feeling tired" usage increased an average of 86 percent, from a 12 percent increase in the non-DST Arizona up to a 231 percent increase in Delaware. By Thursday, "tired" is back to normal.

9. Sleepier Kids (Maybe)

A little girl sleeping with her mouth open.
iStock.com/quintanilla

The studies surrounding DST and school children are surprisingly inconclusive. On the one side, a 2009 article in Sleep Medicine looked at 469 Germans from 10 to 20 years old and divided them up into 'larks' (those who go to bed early and wake up early) and 'owls' (those who go to bed late and wake up late). They found that after the DST transition the group was sleepier for three weeks after the transition, with owls showing higher daytime sleepiness, and proposed that tests shouldn't take place in the week following the switch over to DST.

A 2017 article in Economics of Education Review, however, looked at 22,000 Europeans students and found that, at least for low-stakes tests, the effect wasn't statistically significant.

10. More Cyberloafing on the Job

A woman gets caught cyberloafing at work
iStock.com/Manuel-F-O

Another study looked at people's Google search trends for the Mondays before the switch to DST, immediately after the switch, and a week after, with a specific focus on sites like Facebook, YouTube, and ESPN (i.e. entertainment sites that people probably aren't Googling for their jobs). They found that on the Monday after the switch, people searched for 3.1 percent more entertainment websites than the Monday before DST, and 6.4 percent more than the subsequent Monday. While the researchers caution they can't be sure this was all "cyberloafing," the fact that there was nothing else special about these Mondays meant it very likely was.

11. Mistimed Insulin Shots

A woman injecting herself with an insulin pen.
iStock.com/6okean

It might seem that in this age of smartphones and connected devices that figure it all out, the twice-yearly ritual of finding all the clocks to change is a thing of the past. But that's not necessarily true. In a 2014 article in the Journal of Diabetes Science and Technology, the authors pointed out an easy clock to miss: insulin pumps. Because most commercial pumps aren't GPS-enabled and lack internal time change mechanisms, they have to be manually set up. The study authors discuss an international college student with an insulin pump that came from a country that didn't observe DST, meaning the clock was an hour off. They say that no significant harm resulted, but it just serves as a reminder to make sure you check all your clocks.

12. Higher Energy Bills

Man reviews an energy bill on a tablet app
iStock.com/baloon111

One of the main rallying cries for DST is that it saves energy, but studies have been mixed. In 1975 the Department of Transportation issued a report about whether a short-lived, year-long DST experiment had been worthwhile [PDF]. They declared "modest overall benefits might be realized by a shift from the historic six-month DST system," but cautioned that these benefits were difficult to isolate. Optimistically, though, they said DST might help reduce 1 percent of electricity use.

But as modern researchers have noted, electricity usage has shifted since then. Chief among the changes: Only 46 percent of the new single family households completed in 1975 had air conditioning, compared to 93 percent in 2016 [PDF].

Indiana provided a good place to test this change, because in 2006 they decided to observe DST as an entire state (individual counties had observed DST before). A study ultimately concluded that while DST does save electricity in lighting, this is more than offset by increased demands for heating and cooling, resulting in Indiana households being hit by $9 million per year in higher electricity bills [PDF]. However, the study only looked at residential electricity consumption, not commercial or industrial.

Around the same time, the Department of Energy also looked into DST and found that during a four-week extension, electricity use decreased about half a percentage point per day. Ultimately, Stanton Hadley at the Oak Ridge National Laboratory told Live Science, "I could see the answer being either way."

This story originally ran in 2018.

Amazon's Best Black Friday Deals: Tech, Video Games, Kitchen Appliances, Clothing, and More

Amazon
Amazon

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

Black Friday is finally here, and Amazon is offering great deals on kitchen appliances, tech, video games, and plenty more. We will keep updating this page as sales come in, but for now, here are the best Amazon Black Friday sales to check out.

Kitchen

Instant Pot/Amazon

- Instant Pot Duo Plus 9-in-115 Quart Electric Pressure Cooker; $90 (save $40)

- Keurig K-Cafe Special Edition; $190 (save $30)

- Ninja OS301 Foodi 10-in-1 Pressure Cooker and Air Fryer; $125 (save $75)

- Nespresso Vertuo Next Coffee and Espresso Machine by Breville; $120 (save $60)

- KitchenAid KSMSFTA Sifter with Scale Attachment; $95 (save $75)

- Keurig K-Mini Coffee Maker; $60 (save $20)

- Cuisinart Bread Maker; $80 (save $97)

- Anova Culinary Sous Vide Precision Cooker; $139 (save $60)

- Aicook Juicer Machine; $35 (save $15)

- JoyJolt Double Wall Insulated Espresso Mugs - Set of Two; $14 (save $10)

- Longzon Silicone Stretch Lids - Set of 14; $16 (save $11)

- HadinEEon Milk Frother; $37 (save $33)

Home Appliances

Roomba/Amazon

- iRobot Roomba 675 Robot Vacuum with Wi-Fi Connectivity; $179 (save $101)

- ASAKUKI 500ml Premium Essential Oil Diffuser; $22 (save $4)

- Facebook Portal Smart Video Calling 10 inch Touch Screen Display with Alexa; $129 (save $50)

- Bissell air320 Smart Air Purifier with HEPA and Carbon Filters; $280 (save $50)

- Oscillating Quiet Cooling Fan Tower; $59 (save $31)

- TaoTronics PTC 1500W Fast Quiet Heating Ceramic Tower; $55 (save $10)

- Vitamix 068051 FoodCycler 2 Liter Capacity; $300 (save $100)

- Ring Video Doorbell; $70 (save $30)

Video games

Sony

- Marvel's Spider-Man: Game of The Year Edition for PlayStation 4; $20 (save $20)

- The Legend of Zelda: Link's Awakening; $40 (save $20)

- Hyrule Warriors: Age of Calamity; $50 (save $10)

- Marvel's Avengers; $25 (save $33)

- The Last of Us Part II for PlayStation 4; $30 (save $30)

- LEGO Harry Potter: Collection; $15 (save $15)

- Ghost of Tsushima; $40 (save $20)

- BioShock: The Collection; $20 (save $30)

- The Sims 4; $24 (save $20)

- God of Warfor PlayStation 4; $10 (save $10)

- Days Gonefor PlayStation 4; $20 (save $6)

- Luigi's Mansion 3 for Nintendo Switch; $40 (save $20)

Computers and tablets

Microsoft/Amazon

- New Apple MacBook Pro 16 inches with 512 GB; $2149 (save $250)

- Microsoft Surface Laptop 3 with 13.5 inch Touch-Screen; $1200 (save $400)

- Lenovo ThinkPad T490 Laptop; $889 (save $111)

- Amazon Fire HD 10 Tablet (64GB); $120 (save $70)

- Amazon Fire HD 10 Kids Edition Tablet (32 GB); $130 (save $70)

- Apple iPad Mini (64 GB); $335 (save $64)

- Vankyo MatrixPad S2 Tablet; $120 (save $10)

Tech, gadgets, and TVs

Apple/Amazon

- Apple Watch Series 3 with GPS; $120 (save $79)

- Seneo Wireless Charger, 3 in 1 Wireless Charging Station; $16 (save $10)

- SAMSUNG 75-inch Class Crystal 4K Smart TV; $998 (save $200)

- Nixplay 2K Smart Digital Picture Frame 9.7 Inch Silver; $238 (save $92)

- All-New Amazon Echo Dot with Clock and Alexa (4th Gen); $39 (save $21)

- MACTREM LED Ring Light 6" with Tripod Stand; $16 (save $3)

- Amazon Fire TV Stick with Alexa Voice Remote; $28 (save $12)

- DR. J Professional HI-04 Mini Projector; $93 (save $37)

Headphones and speakers

Beats/Amazon

- Beats Solo3 Wireless On-Ear Headphones; $120 (Save $80)

- Apple AirPods Pro; $169 (save $50)

- Anker Soundcore Upgraded Bluetooth Speaker; $22 (save $8)

- Powerbeats Pro Wireless Earphones; $175 (save $75)

- JBL Boombox; $280 (save $120)

Movies and TV

HBO/Amazon

- Game of Thrones: The Complete Series; $115 (save $89)

- Jurassic World 5-Movie Set; $23 (save $37)

- Deadwood: The Complete Series; $42 (save $28)

- Back to the Future Trilogy; $15 (save $21)

Toys and Games

Amazon

- Awkward Family Photos Greatest Hits; $15 (save $10)

- Exploding Kittens Card Game; $10 (save $10)

- Cards Against Humanity: Hidden Gems Bundle; $14 (save $5)

- LOL Surprise OMG Remix Pop B.B. Fashion Doll; $29 (save $6)

- LEGO Ideas Ship in a Bottle 92177 Expert Building Kit; $56 (save $14)

Furniture

Casper/Amazon

- Casper Sleep Element Queen Mattress; $476 (save $119)

- ZINUS Alexis Deluxe Wood Platform Bed Frame; $135 (save $24)

- ROMOON Dresser Organizer with 5 Drawers; $59 (save $11) 

- AmazonBasics Room Darkening Blackout Window Curtains; $26 (save $5)

- Writing Desk by Caffoz; $119 (save $21)

- SPACE Seating Office Support Managers Chair; $112 (save $116)

- Rivet Globe Stick Table Lamp; $53 (save $17)

- Christopher Knight Home Merel Mid-Century Modern Club Chair; $188 (save $10)

- Walker Edison Furniture Industrial Rectangular Coffee Table; $121 (save $48)

Beauty

Haus/Amazon

- MySmile Teeth Whitening Kit with LED Light; $21 (save $12) 

- Cliganic USDA Organic Lip Balms Set of Six; $6 (save $4)

- HAUS LABORATORIES By Lady Gaga: LE RIOT LIP GLOSS; $7 (save $11)

- Native Deodorant for Men and Women Set of Three; $25 (save $11) 

- BAIMEI Rose Quartz Jade Roller & Gua Sha; $14 (save $3)

- Honest Beauty Clearing Night Serum with Pure Retinol and Salicylic Acid; $20 (save $8)

- WOW Apple Cider Vinegar Shampoo and Hair Conditioner Set; $30 (save $5) 

- La Roche-Posay Effaclar Purifying Foaming Gel Cleanser; $15 (save $5)

- wet n wild Bretman Rock Shadow Palette; $9 (save $6)

- EltaMD UV Daily Tinted Face Sunscreen Moisturizer with Hyaluronic Acid; $25 (save $6)

Clothes

Ganni/Amazon

- Ganni Women's Crispy Jacquard Dress; $200 (save $86) 

- The Drop Women's Maya Silky Slip Skirt; $36 (save $9)

- Steve Madden Women's Editor Boot; $80 (save $30)

- adidas Women's Roguera Cross Trainer; $40 (save $25)

- Line & Dot Women's Elizabeth Sweater; $74 (save $18)

- Levi's Men's Sherpa Trucker Jacket; $57 (save $41)

- Adidas Men's Essentials 3-Stripes Tapered Training Joggers Sweatpants; $28 (save $12)

- Timex Men's Weekender XL 43mm Watch; $32 (save $20)

- Ray-Ban Unisex-Adult Hexagonal Flat Lenses Sunglasses; $108 (save $46) 

- Reebok Men's Flashfilm Train Cross Trainer; $64 (save $16)

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25 Offbeat Holidays You Can Celebrate in December

ivanastar/iStock via Getty Images
ivanastar/iStock via Getty Images

Whether you're a holiday fanatic who wants even more to celebrate, or a Scrooge with a burning desire to buck tradition, we've got plenty of offbeat observances to put on your calendar.

1. December 1: Giving Tuesday

After indulging on Thanksgiving, and shopping on Friday, Monday, and probably the whole weekend in between, Giving Tuesday—which occurs annually on the Tuesday following Thanksgiving—encourages people to engage in charitable activities.

2. December 4: National Cookie Day

ThitareeSarmkasat/iStock via Getty Images

December isn’t exactly lacking in opportunities to indulge in sweet treats, but today it’s your offbeat-holiday-given right to mix, bake, and/or eat as many cookies as you can handle.

3. December 5: Bathtub Party Day

There's a lot to be done between now and the end of the year. Take a minute to breathe, relax, and take in a soak.

4. December 5: International Ninja Day

The official website of Ninja Day alleges this holiday not only honors all things stealth and nunchucks, but also combats the more nautical offbeat holiday Talk Like a Pirate Day, which takes place in September. Creep, sneak, or redirect all of your URLs to Ninja activity—as long as you forgo the “arrrr matey’s” and eye patches for ominous silence and masks, you’re correctly celebrating this international holiday.

5. December 6: National Pawnbrokers Day

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If you thought good ol' St. Nicholas was the patron saint of reindeer and stockings, think again: The actual Nikolaos of Myra was the patron of things like the falsely accused and pawnbrokers, and on this day we acknowledge the latter.

6. December 9: Weary Willie Day

Professional clown Emmett Kelly created one of the more memorable clown characters of the 20th century: “Weary Willie.” Unlike many of his clown predecessors, Weary Willie opted out of white face paint and broad slapstick for the “tramp” look popular among Depression-era derelicts. One of his signature routines involved attempting to sweep up after circus acts, and failing in spite of himself—to the delight and empathy of the audience.

7. December 10: Jane Addams Day

December 10 is the day that the Nobel Prize Award Ceremonies have been held every year since 1901. Consequently, there are a lot of firsts that fall on this date, like the first American woman to be honored. That would be Jane Addams, founder of our current social work industry and prominent women's suffrage leader. On the anniversary of that award, given in 1931, we remember her life and work.

8. December 11: Official Lost And Found Day

Visit a thrift store, see if you can find that book you’ve misplaced, or invest in a memory-boosting regime so you’ll be losing things less frequently.

9. December 12: Poinsettia Day

alicjane/iStock via Getty Images

This day doesn't just celebrate the festive flower—it also marks the death of its namesake, Joel Roberts Poinsett. The botanist (and first U.S. Ambassador to Mexico) brought clippings of Euphorbia pulcherrima back to the States from southern Mexico, and grew the plant at his South Carolina home.

10. December 12: Gingerbread Decorating Day

Whether you’re a craftsman or an eater, today is the day for you.

11. December 13: National Day Of The Horse

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In 2004, the Senate signed legislation to officially make the second Saturday of December the National Day of the Horse. We really shouldn’t have to explain the reason horses need to be celebrated—just look at them!

12. December 13: National Cocoa Day

The weather outside is starting to get frightful, but what better cure for the temperature blues than a nice cup of hot cocoa? A down coat or a wool hat simply can’t compete in the taste department.

13. December 14: Monkey Day

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Officially, Monkey Day is an “annual celebration of all things simian, a festival of primates, a chance to scream like a monkey and throw feces at whomever you choose.” The origins of the holiday are unknown, though it has been observed since at least 2003.

14. December 15: Cat Herders Day

Technically this day is for all those who work jobs that could be described as like trying to herd cats, but it’s also probably acceptable to celebrate by trying to wrangle a cute feline.

15. December 16: Barbie And Barney Backlash Day

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Doesn’t seem like a coincidence that this holiday occurs in December: It’s the one day a year when you can tell your kids that Barbie and Barney don’t exist.

16. December 17: Wright Brothers Day

Made an official holiday in 1963 by Presidential Proclamation, this holiday marks the day in 1903 when Orville and Wilbur Wright achieved the first ever successful (documented) controlled airplane flight near Kitty Hawk, North Carolina.

17. December 18: Underdog Day

Observed annually on the third Friday of December since 1976, this is a reminder to honor the little guy. We’re always rooting for them, but there’s a holiday to celebrate, too.

18. December 21: Humbug Day

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Get out all your bahs and scowls and growls now: no one will tolerate them come Christmas.

19. December 21: Phileas Fogg Win A Wager Day

In Jules Verne's 1873 classic novel Around the World in 80 Days, Phileas Fogg bets that he can travel the entire globe, between 8:45 p.m. on October 2, and 8:45 p.m. on December 21. Keep an eye out for him on this day.

20. December 22: Forefathers’ Day

On December 21, 1620 (it was a Monday) the Pilgrims aboard the Mayflower landed in Plymouth, Massachusetts, and since that basically kick-started our country's history since then, we celebrate it.

21. December 23: Festivus!

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For those who shy away from the more traditional December holidays, there’s always Festivus for the rest of us. Created by a Seinfeld writer's father and popularized by Frank Costanza, this secular holiday that involves gathering around an aluminum pole and airing your grievances has continued to gain a following since its introduction in 1997. If you haven’t seen the episode, there’s an entire website that spells out how to celebrate Festivus from start to finish. (Test your Festivus knowledge with this quiz.)

22. December 25: A’phabet Day

A pun on noel, this offbeat ce'ebration is designed to high'ight the arbitrary nature of many of the year's si''ier ho'idays. Whi'e you're unwrapping presents and eating your Christmas feast, 'eave a'' the Ls out of written and spoken communication for a festive activity that wi'' sure'y infuriate your 'oved ones.

23. December 26: National Whiners Day

Get it all out, whiners. Today is your day.

24. December 29: Tick Tock Day

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In case you needed another reminder of the inevitable passage of time and/or an occasion to reevaluate how those 2019 resolutions are going!

25. December 31: Make Up Your Mind Day

Tomorrow’s a new year! Time to fight that indecisiveness and make a decision—maybe even a resolution, if you will.