Daylight Saving Time full guide part -1 : What, Why, and When?

Daylight Saving Time (DST) is the practice of shifting the clocks forward one hour from standard time during the summer months, then back again in the autumn, in order to make greater use of natural daylight. DST is also known as daylight time, summer time, or daylight savings time in various parts of the globe.

Key Takeaways

What is Daylight Saving Time?

The idea of DST was first proposed by Benjamin Franklin in 1784, in a satirical letter to the editor of The Journal of Paris. Franklin suggested that waking up earlier in the summer would economize on candle usage and calculated considerable savings¹. However, he did not intend his proposal to be taken seriously.

The first serious proposal for DST was made by George Hudson, a New Zealand entomologist and astronomer, in 1895. Hudson submitted a report to the Wellington Philosophical Society, advocating a two-hour change in clocks every spring and fall. He argued that this would allow more time for leisure and scientific activities in the evening.

The first country to apply DST on a national basis was Germany, in 1916, during World War I. The German government thought that DST would conserve coal and aid the war effort. Soon, other European nations including the United States followed suit.

Today, DST is used in over 70 countries around the world, affecting more than one billion people. However, the dates and duration of DST vary from place to place, and some countries have abolished or stopped using DST altogether.

Why is Daylight Saving Time used?

The main rationale for DST is to save energy by reducing the need for artificial lighting in the evening. According to some studies, DST can reduce electricity consumption by up to 5%. However, the actual impact of DST on energy use depends on many factors, such as the climate, the latitude, the type of lighting, and the behavior of consumers and businesses.

Another reason for DST is to reduce traffic accidents and fatalities by providing more daylight during the evening commute. Some studies have found that DST can reduce the number of crashes by 8% to 11%. However, other studies have challenged this claim, arguing that DST can also increase the risk of accidents in the morning or during the transition periods.

A third reason for DST is to increase outdoor activities, such as sports, recreation, and tourism, by extending the daylight hours into the evening. Some studies have shown that DST can increase physical activity, social interaction, and spending on leisure goods and services. However, other studies have suggested that DST can also have negative effects on health, such as disrupting the circadian rhythm, causing sleep deprivation, and increasing the incidence of heart attacks and strokes.

When is Daylight Saving Time used?

DST is used in many countries in the Northern and Southern Hemispheres, but not near the Equator, where the sunrise and sunset times do not vary enough to justify it. The map below shows the current status of DST around the world.

![DST map]

The table below shows the start and end dates of DST in some of the major countries that use it.

To remember which way to set your clock, you can use the mnemonic “spring forward, fall back”. You set your clock forward one hour in the spring when DST starts, and back one hour in the fall when DST ends.

How to adjust to Daylight Saving Time?

To adjust to DST, it is recommended to gradually shift your sleep schedule by going to bed and waking up 15 to 20 minutes earlier or later a few days before the change. You should also expose yourself to natural light in the morning and avoid bright light in the evening to help your body clock adjust. Avoiding caffeine and alcohol, and following a regular routine of meals, exercise, and relaxation can also help you cope with the time change.

Some people may experience more difficulty than others in adapting to DST, especially those who are sensitive to changes in their sleep patterns, such as children, older adults, and people with chronic conditions. If you have trouble sleeping or feel tired, irritable, or depressed, you may want to consult your doctor or a sleep specialist for advice.