How and when did daylight saving time start?

Benjamin Franklin (who took the saying "early to bed, early to rise" very seriously) was apparently the first person to suggest the concept of daylight saving time, according to David Prerau, author of the book Seize the Daylight: The Curious and Contentious Story of Daylight Saving Time.

While serving as the United States ambassador to France, Benjamin wrote that he had been woken up several times at 6:00 a.m. and noticed that the sun was shining earlier than usual. Franklin realized how much candle and lamp oil could be saved at night if people woke up earlier to go about their daily tasks using natural light.

However, it was not until World War I that daylight saving time was implemented on a large scale. Germany was the first country to adopt it in order to reduce the consumption of artificial lighting and save coal for the war effort. Subsequently, it has been introduced, adjusted, or modified across different historical eras and contexts in response to various energy crises.

Does it really help save energy?

The debate regarding its effectiveness remains open. On the one hand, several studies point out that while nighttime artificial lighting consumption is reduced, these savings can be offset or outweighed by higher energy expenditure in other areas—for example, the increased use of air conditioning when returning home earlier on hot days, or heating costs during dark mornings. On the other hand, official reports from various regions have historically highlighted global (albeit modest) reductions in consumption, with significant differences depending on the climate and geographic location of each territory.

Daylight Saving Time: Healthy or harmful?

Beyond economics and energy, advocates of daylight saving time have always emphasized how it promotes a more active lifestyle and outdoor leisure thanks to longer evenings. In contrast, chronobiologists and health experts warn about its harmful effects. They argue that our internal biological clocks (circadian rhythms) suffer, which can lead to chronic fatigue, reduced productivity, sleep disturbances, and the well-known "social jet lag" caused by the mismatch between morning and evening light.