Daylight saving time
A system that sets clocks forward 1 hour in summer. When scheduling with countries that use it, watch for the time difference changing twice a year.
Daylight saving time (DST) is a system that sets clocks forward 1 hour in summer, when daylight hours are long, to make effective use of daylight. It has been adopted in many countries and regions, mainly in Europe and North America (as of 2026), and in the Northern Hemisphere it usually starts in March and ends between late October and November. In scheduling, the DST switchover easily becomes the reason the start time of an international meeting shifts.
Daylight saving time in major countries
| Country / region | Status | Notes |
|---|---|---|
| United States | In use | Second Sunday of March to first Sunday of November (not observed in Arizona and some other places) |
| EU | Abolition under discussion | The European Parliament passed an abolition proposal in 2019, but it has not been approved by the Council of the EU and has not taken effect (as of August 2026) |
| Japan | Not observed | Implemented in 1948-1951 under GHQ direction, then abolished because it was unpopular |
| Australia | Varies by state | Some states observe it and some do not, so check the state where the other person is located |
The history of daylight saving time in Japan
In Japan, daylight saving time was implemented from 1948 to 1951 under the direction of GHQ (the Allied occupation authorities), but public dissatisfaction grew over longer overtime and disrupted daily rhythms, and it was abolished after only 4 years. In 2018, its reintroduction was discussed by the government and the Liberal Democratic Party as a heat countermeasure for the Tokyo 2020 Olympic and Paralympic Games, but it was shelved that autumn because of the burden of modifying systems and concerns about harmful effects on health.
The effect on scheduling
At the DST switchover times (twice a year), the offset between time zones changes. For example, the time difference between Japan and London is usually 9 hours, but it becomes 8 hours during the UK’s BST (British Summer Time) period. If a recurring meeting is set based on UTC, it adjusts automatically, but if it is fixed to local time, the time must be changed manually.
Practices that prevent mishaps at switchover time
Because Japan has no daylight saving time, the pitfall is that it is hard to feel personally involved in the switchover. For recurring meetings with the US / Europe, the start time in Japan time shifts by 1 hour when the other side switches. Moreover, the US and Europe do not switch on the same dates (the US from the second Sunday of March to the first Sunday of November, the EU from the last Sunday of March to the last Sunday of October), so in March and in October-November there is an in-between period where only one side is on summer time. Because the US starts first in spring and Europe ends first in autumn, during these periods the time differences with the US and with Europe form a different combination from usual. Always register events with time zone information, and for meetings in a switchover week, reconfirm the start time on the previous business day. Just keeping these 2 points greatly reduces this kind of mishap.