SPRING MARKS MANY changes: warmer weather, longer days, flowers peeking across the land. But for many people in the US, the approach of spring also means the start of daylight saving time.
This period, often incorrectly called daylight saving time, begins at 2:00 am local time on the second Sunday in March, when clocks are set forward one hour. Daylight saving time ends at 2:00 am local time on the first Sunday in November, when clocks are turned back one hour.
The idea behind the clock shift is to maximize sunlight in the Northern Hemisphere, as the days start to get longer in the spring and then get shorter in the fall. The logic is that by jumping forward and falling, people add an hour of sunlight to the end of the workday. But the benefits of this change are controversial, and the change may have measurable impacts on health.
What is behind the changes in sunlight?
Seasonal changes in the length of a day come from the Earth’s rotation. Our planet rotates on its axis at a relatively constant angle of 23.4 degrees with respect to its path around the sun. This means that while the equator generally enjoys approximately 12 hours of day and night throughout the year, the same is not true to the north or south.
Summer marks the time to shine in the northern hemisphere. It tilts toward the sun, causing longer, warmer days. Meanwhile, the southern hemisphere plunges into the short days of winter as it moves away from the sun. Six months later, the situation is reversed, and winter takes over the North while light bathes the South.
When did daylight saving time start?
Benjamin Franklin was credited by many for daylight saving time thanks to a possibly satirical letter he wrote for the Journal de Paris in 1784. In the letter, he expressed amazement at seeing the sunrise at six in the morning, much earlier than most. of the Parisians. He once saw the light of day. If that were to change, he writes, the city could save a “vast sum” of candles. However, he never suggested a change in the clocks, instead offering other amusing solutions to the problem that included cannons fired into the street to wake people from sleep, taxes on closed windows, and restrictions on the sale of candles.
Others attribute the idea to George Hudson, a New Zealand entomologist, who in 1895 suggested a two-hour shift to allow more bug hunting after work. Shortly afterward, William Willett proposed a similar idea to avoid wasting daylight, bringing the concept to the Parliament of England in the early 20th century.
It wasn’t until resources became scarce during World War I that Germany decided to go ahead with that plan, implementing the first daylight saving time of 1916 to maximize resource use during daylight hours. The United States soon followed suit, with the country’s first seasonal time change in 1918.
Who observes daylight saving time?
Not everyone is in the clock-changing frenzy. In the United States, Hawaii, and most of Arizona (excluding the Navajo Nation), as well as the territories of Guam, Puerto Rico, American Samoa, the US Virgin Islands, and the Northern Mariana Islands, all options to get out of summertime.
Globally, the popularity of changing clocks also varies. Most of North America, Europe, New Zealand, and some regions in the Middle East are on the annual shift, though each has different start and end dates. But most of Africa and Asia do not change their clocks. South America and Australia are divided on the matter.
Europe’s involvement, however, may soon change. The European Commissioner for Transport, Violeta Bulc, announced in 2018 that the time change of the year, which previously covered March and October, would be the last in the EU. According to the German news service Deutsche Welle, each EU state must decide before April 2019 whether to stay in summer or winter.
Are there benefits for daylight saving time?
To many, change seems intrusive, resulting in missed meetings and sleepy citizens. There can be even more serious effects. Some studies have identified an increase in heart attacks that coincides with jumping forward and a slight decrease when falling backward. Other studies suggest that the time change could be linked to an increase in fatal car accidents, although the effect is small relative to the total number of accidents each year. Other concerns include impacts on the immune system due to the inevitable loss of sleep
What’s more, many studies have questioned whether there have ever been energy savings. A 2008 study by the US Department of Energy suggested that in the US, an additional four weeks of daylight saving time saved about 0.5 percent on total electricity per day. But others conclude that the situation is largely a washout: the last hours of sunlight often reduce electricity consumption during this time, but also spur heavier use of air conditioning at night or higher energy demands for lighting. dark mornings.
Still, those impacts can be location-specific. One study found that daylight saving time caused an increase in energy demand and pollution emissions in Indiana, while another found that it led to a slight reduction in energy use in Norway and Sweden.
These days, the arguments in favor of daylight saving time usually center around the boost that the time shift gives to nighttime activities. People tend to go outside in dim light after work — playing sports, going for a walk, taking the kids to the playground — instead of sitting on the couch. Many outdoor industries, including golf and barbecue, have even promoted daylight savings time, which they say increases profits. The oil industry is also a fan, as people drive more if it’s still dim after work or school.
