Everyday, when I wake up in the morning I really appreciate Japan for good time management, i.e. lack of daylight savings time or DST. Why? Read further.

Roots

Since ancient civilizations humans adjusted daily schedules to the sun more flexibly than modern DST does, often dividing daylight into twelve hours regardless of day length, so that each daylight hour was longer during summer.
Modern DST was first proposed by the New Zealand entomologist George Vernon Hudson, whose shift-work job gave him leisure time to collect insects, and made him aware of the value of after-hours daylight. In 1895 he presented a paper to the Wellington Philosophical Society proposing a two-hour daylight-saving shifts.
Starting on 30 April 1916, Germany and its World War I allies were the first to use DST (ger.: Sommerzeit) as a way to conserve coal during wartime. Britain, most of its allies, and many European neutrals soon followed suit. Russia and a few other countries waited until the next year and the United States adopted it in 1918.

How it works?

In a typical case where a one-hour shift occurs at 02:00 local time, in spring the clock jumps forward from 02:00 standard time to 03:00 DST and that day has 23 hours, whereas in autumn the clock jumps backward from 02:00 DST to 01:00 standard time, repeating that hour, and that day has 25 hours. A digital display of local time does not read 02:00 exactly at the shift, but instead jumps from 01:59:59.9 either forward to 03:00:00.0 or backward to 01:00:00.0. In this example, a location observing UTC+10 during standard time is at UTC+11 during DST; conversely, a location at UTC−10 during standard time is at UTC−9 during DST.

Official benefits

Willett’s 1907 proposal argued that DST increases opportunities for outdoor leisure activities during afternoon sunlight hours. The longer days nearer the summer solstice in high latitudes offer more room to shift daylight from morning to evening so that early morning daylight is not wasted.
DST’s potential to save energy comes primarily from its effects on residential lighting, which consumes, for example, about 3.5% of electricity in the U.S. and Canada. Delaying the nominal time of sunset and sunrise reduces the use of artificial light in the evening and increases it in the morning.

Other side of the coin

These benefits sounds very nice and interesting, however having DST it also means, that people have to reschedule their sleeping and working time at least twice a year. For some this is a huge stress, due to the fact, that all biorhythms are “rescheduled” as well. For example, effects on seasonal adaptation of the circadian rhythm can be severe and last for weeks. A 2008 study found that although male suicide rates rise in the weeks after the spring transition, the relationship weakened greatly after adjusting for season(Ref. Michael Berk; Seetal Dodd; Karen Hallam; Lesley Berk; John Gleeson; Margaret Henry. Small shifts in diurnal rhythms are associated with an increase in suicide: the effect of daylight saving. Sleep and Biological Rhythms. 2008;6(1):22–25.) The government of Kazakhstan cited health complications due to clock shifts as a reason for abolishing DST in 2005.

Personal opinion

I was born in a country where we have two times. First one is a “Decree time” – introduced in the USSR time system from 16 June 1930. By this decree, all clocks in the Soviet Union were permanently shifted one hour ahead of standard time for each timezone. It is totally independent from Daylight Saving Time.
Second one Daylight Saving Time, which was introduced in the USSR much later, in 1981(it was introduced and cancelled several times).
As you can see, with both time shifts in effect, summer time was two hours ahead of standard time in the USSR.
Because of this, moments when time-shifts occurs are especially stressful and painful. That is why I like Japan, for not using DST at all.

As a positive note, yesterday Russian president ordered to prepare a law concerning cancellation of time-shift. So, hopefully the last time when people have stress will be in this spring only.