Päivänvalonsäästöaika

Päivänvalonsäästöaika, often translated as daylight saving time (DST) or summer time, is a practice of advancing clocks during warmer months so that darkness falls at a later hour of the day. In most countries that observe DST, clocks are typically advanced by one hour, usually in the late winter or early spring, and then turned back by one hour in the autumn. The primary stated purpose of this adjustment is to make better use of daylight and save energy.

The concept of DST has been implemented in various forms and at different times throughout history. Modern implementation of DST is often credited to Benjamin Franklin, though his suggestions were more satirical and not a direct proposal for the system as it exists today. The first widespread implementation of DST occurred in Germany and its ally Austria-Hungary during World War I, on April 30, 1916. Many other countries soon followed suit. The goal was to conserve coal during wartime by reducing the need for artificial lighting.

In Finland, päivänvalonsäästöaika has been practiced intermittently. The current system has been in place since 1981, aligning with the European Union's directive on daylight saving time. Clocks are moved forward one hour on the last Sunday in March and back one hour on the last Sunday in October. While intended to save energy and better utilize daylight, the effectiveness and benefits of DST are a subject of ongoing debate, with discussions about its impact on health, energy consumption, and economic activities.