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For some, the cost of an hour of sleep caused by daylight savings outweighs the benefits of extended sunlight.

March 15, 2021

Daylight Saving Time Strains Sleep Health

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Daylight saving time, a centuries-old practice to save daylight and reduce energy costs back when candles were still burned at night, has turned into an inconvenience for Cornellians — and many Americans — twice a year. 

At 2 a.m. on Sunday, Cornell students saw their phone clocks spring forward an hour. Aside from causing general confusion about the time, daylight savings can have a profound impact on individual health because of the loss of sleep.

“Even when you have just a one hour interruption of your regular sleep cycle, we can find effects that last up to four days,” said Prof. Nicolas Ziebarth, policy analysis and management. “In the spring, you lose an hour of sleep. If you do not adjust your behavior, you will be tired.”

In his research paper, “Sleep, Health and Human Capital: Evidence from Daylight Saving Time,” Ziebarth examined the negative effects of sleep deprivation on human health, as well as the significant health benefits to increasing sleep. In the study’s findings, the additional hour of sleep gained at the end of daylight savings in November was associated with a significant reduction in hospital admissions, heart attacks and injuries for four days afterward in Germany.

“The findings from our study reinforce the need to devise policies to reduce sleep deprivation in the population,” the paper reads.

Although one hour may seem like a small amount of time, losing that hour to daylight savings can exacerbate the health and productivity of many already chronically sleep deprived Cornell students. According to Cornell Health, nearly 25 percent of students surveyed indicate that sleep deprivation impaired their academic performance.

Michael Liang ’24, who sleeps only five to six hours a night, is one of those students. 

“When I don’t get at least five hours of sleep, I get really tired and start losing focus,” Liang said. “I have to make sure to catch up on sleep during the weekend. Daylight saving time might make this worse for me.”

But according to Ziebarth, getting seven to nine hours of sleep each night should be a priority for students.

“I feel that students underestimate how important sleep is and to get a regular seven to nine hours a night,” Ziebarth said. “It’s not enough to sleep less than seven hours on a regular basis, let alone six.” 

By not allowing brain cells to recuperate at night, sleep deprivation results in slower thinking and impaired memory — both of which are critical for college students’ health and academic performance.

Ziebarth also cautioned against the regular use of caffeine or energy drinks to compensate for a lack of sleep. Using artificial means to replace energy lost to sleep deprivation can lead to side effects and addiction that students can avoid by following the human body’s natural clock.

To counter the one-hour shift, Ziebarth suggested going to bed earlier and trying to fall asleep. Experts recommend that a few days before daylight saving time, people should go to bed half an hour or 10 minutes earlier every day to adjust.

But daylight saving time still has its benefits, offering increased sunlight during waking hours.

By shifting clocks to better align with sunrise and sunset, people — especially in northern regions of the globe — can enjoy brighter days. Others defend daylight savings in the name of economic benefits, such as increased worker productivity and boosted sales for restaurants and stores as people leave their homes more often with longer daylight.

Adjusting the time to extend sunlight can even help with medical conditions, such as Seasonal Affective Disorder, in which consistent lack of sunlight contributes to symptoms of depression.

Although there are benefits to daylight savings, many are still frustrated by the inconvenience it causes — 63 percent of American adults support eliminating daylight savings. Some states, like Hawaii and most of Arizona, have rejected daylight savings altogether.

“If we don’t want to change our clocks twice a year, we need to agree on whether it should be summertime all year long or wintertime all year long,” Ziebarth said. Clocks stay one hour ahead in summer and fall back an hour in November.

Daylight saving time will end Nov. 7, forcing those who practice daylight savings to “fall back” in about eight months or risk missing important meetings and dates.  

“This affects basically everybody, and you can see in the data that it does matter, even if it is just one hour,” Ziebarth said.