It is getting to that time of year when the clocks will once again go back due to daylight saving time.
This will happen on November 5 at 2 a.m. local time. Although this means the morning and evenings get darker, we do gain an extra hour of sleep.
Most of North America experiences daylight saving time, but not all. There is the exception of most of Arizona and Hawaii. Some U.S. territories—American Samoa, Guam, the Northern Mariana Islands, Puerto Rico and the U.S. Virgin Islands— also do not use daylight saving time.
Daylight saving time will start once again in March, where the clocks spring forward, meaning we have lighter mornings and evenings, but lose an hour of sleep.
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Why Does Daylight Saving Exist?
Daylight saving time was implemented in the U.S. in 1918, in order to maximize the sunlight hours in the Northern Hemisphere.
By changing the clocks back and forward, in conjunction with the seasons (when daylight extends in the spring and reduces in the fall) there is an additional hour of light to the working day.
The concept was adopted during World War I, to maximize resources that were scarce at the time.
Germany was the first country to go ahead with saving time in 1916, before others also adopted the practice. The practice had been discussed at length before then, but never adopted.
The U.S. kept what was then known as “war time” into World War II, as it proved effective at conserving resources such as fuel.
The practice was adopted again during the 1970s energy crisis.
Nowadays, U.S. states are not bound by law to keep using daylight savings time—hence, why Arizona and Hawaii opted out.
How Can Daylight Saving Impact Circadian Rhythm?
Daylight saving time can impact our circadian rhythms. This refers to the mental, physical and behavioral changes a person can experience during a 24-hour cycle, such as levels of tiredness, appetite, and body temperature.
These processes can be altered depending on changes in the lightness and darkness in a person’s environment.
Although it is only a one-hour time shift, it can make a large difference to the levels of darkness observed by a person during the day.
The shift in the fall results in a person having less exposure to morning light and more exposure to evening light, as people’s sleep and work schedules remain the same.
Scientists have found that desynchronization of body clocks twice a year can lead to an increase in health risks such as depression, obesity, cancer and heart attacks.
Continuous studies on how one-hour time shifts can alter the rhythm—which relates to the Earth’s rotation—has sparked debate over whether daylight saving time should still be used.