You Might Need a Helmet to ‘Spring Forward’


Red clock

In March, Daylight Saving Time (DST) begins, and we’ll all “spring forward,” like it or not (that is, all of us in the U.S. except residents of Arizona and Hawaii, anyway). Modern DST began during the Second World War, and has garnered strong opinions both for and against it ever since.

You might have heard that DST was meant to give farmers more light, but there isn’t any truth to that. In fact, DST shifts one hour of morning daylight into the evening, a move that actually increases the amount of time early risers spend in the dark. DST was actually implemented to promote energy saving: by moving the daylight hours to when most people are awake, officials reasoned, people could use less energy. Insurance Journal adds that DST proponents believe the extra evening light, “encourages people to exercise after work and reduces crime and traffic fatalities.”

Opponents argue, though, that the impact of disrupting people’s schedules and sleep may outweigh the benefits. And there is much debate about whether DST saves energy at all, with some arguing it increases energy consumption. Arizona and Hawaii legislators say that part of the reason neither practices DST is that more daylight in the evening incurs more energy use (particularly due to air conditioning). The debate about DST’s usefulness continues, but in the meantime, we all must live with it.

When daylight saving time ends each fall, it isn’t quite so bad—we adjust our schedules, yes, but that extra hour of sleep is nothing to scoff at. But losing an hour in the spring is tough—especially for those living in places where the weather still feels much more like winter. Rising in the cold mornings is even more difficult when it’s dark, too. And study after study proves that DST is more than just an inconvenience; it has real—even potentially deadly—consequences for the estimated 1.5 billion people living in countries that observe it.

Cars on city street at sunrise
Daylight saving time might spell trouble for your morning commute.

Sleep-Disrupted Drivers Increase Crashes by 17 Percent

CBS New York reports that the number of car crashes climbs 17 percent in the first week after daylight saving time when the clocks spring forward. CBS spoke with Sam Schwartz, former New York City traffic commissioner, who explained that the increase in wrecks was due to changes in sleep patterns. Schwartz said it takes several days for people’s circadian rhythms to adjust, and the effects on their driving abilities in the meantime can be substantial.

After DST begins, many people will suddenly be commuting in the dark, which impacts their abilities to drive and thus also plays a large role in the increase in car crashes. TIME spoke with economist David Gerard who said that in the days and weeks following DST, “Even though it’s dark, you’re still behaving like it’s light,” which Gerard says can lead people to drive faster. Pedestrians and cyclists are also at risk: the sudden thrust into morning darkness can catch people with their guards down, and they may be less attentive, Gerard says.

However, proponents of DST argue the switch is worth it, since darkness in the morning means more daylight in the evenings—during the evening commute, and when kids are coming home from sports and activities. TIME spoke with law professor Steve Calandrillo who said, “There are far more people asleep at 7 in the morning than at 7 in the evening.”

If it’s hard to believe just one hour has such an effect on traffic accidents, remember that the morning after the time change, every single person on the road is dealing with fatigue, or at the very least, a disrupted schedule. Whereas on other days your quick thinking might help you avoid a crash with the sleep-deprived drivers around you, if you’re tired too, that near-miss has a greater chance of being severe.

Daylight saving time may increase car crashes, heart attacks, and criminal behavior.

Stress of DST Causes Heart Attacks and Headaches

Daylight saving time’s effects aren’t limited to car crashes: experts say there’s also an increased risk of heart attacks and other health troubles just after the time change. Forbes cites studies that suggest “links between DST and a variety of disturbing social outcomes, including increases in heart attacks and upticks in criminal behavior. And these, in turn, have given rise to a cottage industry in petitions and grassroots movements aimed at ending the biannual tyranny of clock-setting.”

Live Science also details studies showing an increase in heart attacks following the beginning of DST in the spring. They reference a Swedish study that showed, “the rate of heart attacks during the first three weekdays following [DST] increased by about 5 percent from the average rate during other times of the year.” Sleep pattern disruptions, they say, can lead to an increase in stress hormones which increase inflammation—a bad combination that can lead to heart attack for at-risk people.

Post-DST, some people also report increases in cluster headaches, a type of headache in which pain severe enough to wake a person from sleep is centralized, often behind one eye, and symptoms may recur for days or weeks. It seems the disruption in circadian rhythm is to blame here, too: big changes in bodily hormones can result from even small sleep disruptions like rising an hour earlier.

DST Increases Workplace Injuries

While office workers might not be at risk of bodily harm due to DST-induced sleep deprivation, the risks for people working physical jobs with heavy machinery can be substantial.

Live Science reports that people working “physically taxing jobs, such as miners, have been shown to experience more frequent and severe workplace injuries at the onset of daylight saving time in the spring.” Live Science cites a 2009 Journal of Applied Psychology study that found “mine workers arrived at work with 40 minutes less sleep and experienced 5.7 percent more workplace injuries in the week directly following the springtime daylight saving transition than during any other days of the year.” Researches concluded that the increased injuries were caused by less sleep.

It’s worth noting that all these effects—the increases in car crashes, heart attacks, and workplace injuries—did not appear in the fall when DST ends. The extra hour of sleep, it seems, acts as a buffer for the negative effects of altering the clocks.

More sleep-and coffee-may help combat effects of DST.
More sleep-and coffee-may help combat effects of DST.

How to Combat the DST Dangers? Get. More. Sleep.

CBS New York suggests “people get extra sleep and, if possible, try to arrive at work a little later than usual Monday.” Also, anyone driving should be on high alert, especially on the Monday morning and the first few days after the change.

It seems to us that the sudden switching back and forth is the greatest threat to people living in places that observe DST, rather than the movement of daylight hours themselves. None of the negative effects—car crashes, heart attacks, or workplace injuries—went on longer than a few weeks after DST began.

Perhaps we could all benefit from the wisdom of people with young children (those members of society least amenable to sudden schedule changes). Parents of young children know to ease them into DST for at least a week before the clocks officially change. There’s nothing quite like a four-year-old who refuses to change out of pajamas for school because, as they rightly note, the sun hasn’t even come up yet when just the day before sun streamed through the windows during their morning routine.

So, if your schedule allows it, consider going to bed a little earlier each night leading up to the time change—and set your alarm a little earlier each morning. It might quiet the protestations of your inner toddler the Monday after the time change.