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The dark side of daylight saving time

What are we sacrificing for afternoon sunlight in winter? Morning light. If daylight saving time becomes permanent, it means 57 days of darkness until 8 a.m. for Boston.

The US Senate advanced a bill on March 15 that would bring an end to the twice-yearly changing of clocks, in favor of a "new, permanent standard time" that would mean brighter winter evenings.CHRIS DELMAS/AFP via Getty Images

Many of America’s leading sleep scientists and researchers spent this week in Rome. They were attending the annual World Sleep Congress, discussing the importance of regular sleep and circadian rhythms. Meanwhile, in Washington, D.C., the Senate swiftly and unanimously passed a bill to make daylight saving time permanent.

One of the American sleep scientists in Rome, Dr. Candice Alfano, said she laughed when she found out. “A host of top sleep and circadian scientists leave the US for a few days to discuss (among other things) the dangers of daylight saving time, so the US government picks the same moment to push for permanent daylight saving time?” she said over email. “It’s fitting with our government’s overall relationship with science.”


The scientists weren’t the only ones caught off guard. When the Sunlight Protection Act glided through the Senate, the senators themselves were also caught unawares. Republican Senator Tom Cotton of Arkansas, an opponent of making daylight saving time permanent, reportedly was not told by his staff the bill was being debated. Republican Senator Rick Scott of Florida said he would have made a speech in support of the bill if he had known.

The scientists are happy that the Senate has proposed an end to changing our clocks twice a year. They are less delighted about the push to make daylight saving time permanent. To them, the science is obvious: Standard time aligns with our natural circadian rhythms and the sun, so why mess with it?

The belief is that more daylight in the late afternoon is beneficial. “More smiles,” “more sunshine and less depression,” are the motivations.

So what are we sacrificing for this bonus afternoon sunlight in winter? Morning light. If daylight saving time does become permanent, it means 57 days of darkness until 8 a.m. for Boston, compared with zero days with standard time. Sunrise in Seattle would be pushed to nearly 9 a.m. for many days a year.


According to scientists, a lack of morning light can lead to sleep and metabolic disorders, depression, and cardiovascular disease, among other ailments. Exposing ourselves to less light in the morning for more light in the afternoon leads to sleep deprivation; the Centers for Disease Control and Prevention declared sleep deprivation a national endemic in 2014.

Daylight saving time causes circadian misalignment — our bodies are not synched to the sun or to social clocks. Contrary to popular belief, it’s not just the first week after the clock changes that we lose out; it’s a chronic circadian misalignment.

There is no data to prove that our circadian clocks catch up with daylight saving time, even after eight months of it. Now it seems we could be an hour off our natural time for as long as it takes the government to realize that they should’ve switched to standard time.

In support of permanent daylight saving time, Senator Sheldon Whitehouse of Rhode Island told the Senate: “There are a lot fewer people up and about between 6:30 and 7:30 in the morning than there are between 4:15 and 5:15 in the afternoon.” He was playing a numbers game, and his numbers are true.

But what is also true is that people of color and those from lower socioeconomic backgrounds suffer more under daylight saving time. These groups have less flexible work schedules and their days begin earlier. The average person loses 19 minutes of sleep a night through all of daylight saving time, but those who go to work before 7 a.m. lose 36 minutes a night.


An early activist of daylight saving time was William Willet, a British builder and an avid golfer. Decades later, the golfers are still looking for ways to prolong their rounds. Some lobbyists for permanent daylight saving time include the golf industry, candy companies who want it to last through Halloween, the BBQ industry, and the fuel lobby. “Daylight saving time may be better for niche businesses, but it’s worse for public health and the economy,” said Dr. Karin Johnson, medical director of Baystate Health’s Regional Sleep Program in Springfield.

The argument that daylight saving time saves on energy has also been debunked. We save a little bit in lighting, but we spend a lot more in air conditioning, heating, and gas. Daylight saving time may have conserved energy in 1918 when the United States first implemented it, but since then we have drastically changed the ways in which we use energy.

Why, then, are so many politicians adamant on daylight saving time? One explanation is that data against seasonal clock change and in support of standard time was staggered. First the data proved that changing our clocks was dangerous, that it could lead to an increase in heart attacks and suicides, among other things. By 2014, data showed that standard time was healthier for us than daylight saving time.


Passing the Sunshine Act in the most sleep-deprived week of the year was meant to bring the country together. Everyone did appear united in ending seasonal clock change, but what the politicians were probably not expecting was the backlash against daylight saving time. It seems that it’s only a matter of time before everyone realizes that we need to make standard time permanent.