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November 5, 2017
by Tracey Block

"Fall Back" Brings Forward Theories On its Effects

November 5, 2017 08:00 by Tracey Block  [About the Author]

Spring forward - fall back. More than one billion people in 70 countries just turned their clocks back an hour, ending another year of Daylight Saving Time (DST) and returning to Standard Time (ST). While the idea of enjoying that one extra hour of sleep stolen back in the spring is wonderful, psychologists, physicians and researchers began broadcasting wary messages days ahead of the changeover, warning of potential fatigue, distracted driving, depression, and increased fatalities.

Historically, it was in the late 1700s, recognizing early morning sunlight was under-utilized, scientist and inventor Benjamin Franklin mused about saving daylight in a letter to the editor of the Journal of Paris. Franklin believed acclimatizing to time changes would be quick: “All the difficulty will be in the first two or three days; after which the reformation will be as natural and easy as the present irregularity.”

Winston Churchill, twice Prime Minister of the United Kingdom in the 1940s and ‘50s, also supported the time change, optimistically describing it as “[a]n extra yawn one morning in the springtime, an extra snooze one night in the autumn.”

Franklin and Churchill got their wishes when the DST became federal law in 1918. A blog explains the DST was repealed after World War I; it was used again during WWII. And by 1966, US Congress established the DST to begin on the last Sunday of April and end on the last Sunday of October each year. In 2005, the Energy Policy Act changed the dates to lengthen the DST--beginning each year on the second Sunday in March at 2:00 am, changing back to Standard Time on the first Sunday in November.

In his 2016 article, The Case for and Against Daylight Saving Time in National Geographic, writer Brian Handwerk quotes Tufts University professor Michael Downing, author of Spring Forward: The Annual Madness of Daylight Saving Time: “I think the principal annoyance is that it’s confusing.”

Benjamin Franklin could never have predicted the impact of his biannual fluctuations, but more than causing confusion, the time change is blamed for its unforeseen effects on human physical and mental health.

According to Handwerk’s article, scientific studies of the impacts of the DST have produced mixed results. “Two studies, conducted in the United States and Sweden, found that heart attack risk increased by up to 25 percent on the Monday after we move the clocks ahead,” he wrote. “The same researchers found that the risk dropped by 21 percent when the clocks fall back.”

Chronobiologist Till Roenneberg believes the body’s circadian clock (its natural regulator) never completely adjusts to the changes in DST or ST hours. In Handwerk’s National Geographic article, he explains: “. . . while more morning light helps jump-start our bodies, the extra evening light leads to lag . . . decreased productivity, decreased quality of life, increasing susceptibility to illness, and [people who are] just plain tired." 

As mentioned, many people cannot wait to regain that extra hour of sleep when Standard Time returns, yet new research finds even that change back may cause increased acts of aggression. And such statistics clearly run counter to our expectations. One can expect someone to be crankier and/or behave more aggressively after losing an hour of sleep—as is the case in the spring. But increased aggression after more sleep?

Rick Nauert, PhD, in his post, Changes in Daylight Savings Time Increase Aggression, for, explains a study by University of Pennsylvania criminology doctoral student Rebecca Umbach, with her professor, Adrian Raine, and criminologist Greg Ridgeway. The three hypothesized that on the Monday following the loss of an hour’s sleep due to the start of DST, “people would become more antagonistic.”

Surprisingly, Umbach’s results were just the opposite. The assault rate on those Mondays after the change to DST actually dropped by three percent. And in the fall, when the lost hour of sleep was regained, the three researchers noted a three percent rise in assaults.

“Sleep problems have previously been associated with increased antisocial and criminal behavior, so we were surprised to find that increased sleep was associated with increased offending,” Professor Raine explained. “This discrepancy is likely due to the fact that 40 to 60 minutes of lost sleep in one night is just not the same as months, or even years, of poor sleep.”

Moving the day forward or back by an hour can indeed throw the sleep cycle into turmoil. To adjust more easily next time, suggests ensuring you are caught up on sleep in the week leading up to the change. Use light to your advantage--soak up the morning sunlight; dim your lights at night to help your body recognize time for sleep; and limit nighttime computer use. Finally, pay attention to evening routines: limit alcohol and caffeine, and save workouts for the daytime.

The ongoing attempt to use daylight to human advantage by controlling time—to the detriment of natural and emotional rhythms--remains controversial. Physical, emotional and psychological effects on the human psyche produce opposing scientific evidence. And the question of whether the DST-ST time changes will continue or not is asked every year--with conflicting responses. For now, it seems, we’ll just have to sleep on it.



Handwerk, B., (November 3, 2016). The Case for and Against Daylight Saving Time. National Geographic.

Nauert, R., PhD, (Retrieved November 4, 2017). Changes in Daylight Savings Time Influence Aggression. PsychCentral.

Serratore, A., (March 8, 2013). Did Benjamin Franklin Invent Daylight Savings Time? (Retrieved November 4, 2017). Why Do We “Spring Forward” But “Fall Back” With Daylight Saving Time?


About the Author

Tracey Block
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