Open to download resource.
Historical Implementation (1948–1951)
Daylight Saving Time (DST) was briefly introduced in post-war Japan from 1948 to 1951 under the initiative of the General Headquarters of the Allied Powers (GHQ).
• Reasons for Abolition: The system was abolished upon the signing of the San Francisco Peace Treaty due to several factors, including an increase in overtime work, chronic sleep deprivation, and a lack of public consensus.
---------------------------------------------------------------
Since then, there have been several instances where the introduction of Daylight Saving Time posed a significant concern; however, on each occasion, the JSSR has taken decisive action in opposition.
1. House of Councillors "Subcommittee on the Daylight Saving Time System" (2004–2005)
The most substantive legislative discussions took place in the mid-2000s within the House of Councillors.
• Establishment: The subcommittee was formed within the Committee on Economy, Trade and Industry of the House of Councillors.
• Background: Discussions were led primarily by the supra-partisan "Parliamentary League for the Promotion of Daylight Saving Time," with the objectives of addressing global warming (energy conservation) and reforming lifestyles.
• Outcome: While the business community expressed support, the proposal failed to reach the stage of bill submission due to strong public opposition and the prohibitive costs associated with IT system modifications.
Response of the Japanese Society of Sleep Research (JSSR):
The Japanese Society of Sleep Research established the "Special Committee on the Daylight Saving Time System" to conduct extensive evaluations. The committee’s findings were compiled into two reports: "Daylight Saving Time and Sleep (Interim Report, April 2005)" and "Daylight Saving Time and Sleep (Final Report, July 2008)," both of which are available on the JSSR website.
In March 2012, the Special Committee also produced a booklet (attached) formally opposing the DST system, which continues to be distributed through the Society’s website and other channels.
2. Deliberations for the 2020 Tokyo Olympics (2018)
In 2018, as a countermeasure against extreme heat for the Tokyo Olympics, a "Study Group for the Introduction of Daylight Saving Time" was established within the Liberal Democratic Party under the Abe administration.
• Proposal: The discussions included a plan to advance the nation's clocks by two hours to effectively schedule athletic events during cooler early-morning hours.
• Conclusion of Discussions: Within a few months, the proposal was effectively scrapped due to fierce backlash from the IT industry regarding unfeasible system update timelines, as well as concerns over health risks, including sleep deprivation and heatstroke.
Role of the Science Council of Japan and JSSR:
When the DST debate resurfaced in 2018, the Science Council of Japan (SCJ) issued a definitive recommendation to "forego the introduction of the system" based on scientific evidence. Of the 14 members on the relevant SCJ committee, three were Board Members or Councilors of the JSSR. Furthermore, a related symposium held on May 28, 2017, was co-organized by the SCJ, the JSSR, the Japanese Society for Chronobiology, and the Japanese Society of Mood Disorders.
During the 2018 deliberations, the JSSR issued presidential statements and working group reports to sound an alarm based on medical and scientific grounds.
________________________________________
As demonstrated above, the Japanese Society of Sleep Research has consistently expressed strong opposition from the specialized perspectives of sleep medicine and chronobiology whenever the introduction of DST has been proposed in Japan. To date, Daylight Saving Time has not been implemented in Japan since its abolition in 1951.
Document is in Japanese; English translation of the first page is as follows:
Introduction Over the past 20 years there have been repeated efforts to introduce Daylight Saving Time (commonly known as “summertime”), which has been implemented in many developed countries, into Japan. The primary purposes have varied—sometimes energy savings, sometimes a more relaxed lifestyle, and sometimes economic stimulation—so the goals are not always the same. In discussions about introducing summertime in Japan, many issues have been debated, but health effects have been scarcely addressed.
About ten years ago, the Japan Society of Sleep Research established a "Special Committee on the Daylight-Saving Time System" to examine this issue. The committee’s findings are summarized on the Society’s website in "The Daylight-Saving Time System and Sleep" (interim report: April 2005) and "The Daylight-Saving Time System and Sleep" (final report: July 2008). We concluded that, compared with Western countries, Japan has progressed further toward shorter sleep durations and a more evening-oriented lifestyle, so the health impact of introducing summertime in Japan would be large. Moreover, improvements in electrical appliances mean that any energy-saving effect of summertime is now minimal; indeed, energy use in ordinary households could even increase. For these reasons, we concluded that summertime in Japan would bring more disadvantages than benefits.
Meanwhile, some countries that had implemented daylight saving—such as Russia—have abolished the system for reasons consistent with our findings. However, immediately after the Great East Japan Earthquake last year, some government officials and media voices advocated introducing summertime for the purpose of "energy conservation." At that time, the proposal was shelved because it would "add to confusion" and would require an initial investment of about one trillion yen for equipment, among other reasons. Even then, health issues were hardly discussed.
We were concerned that the general public lacked sufficient understanding of the health implications of daylight saving, so we prepared this booklet to explain, in an accessible way and with a focus on health effects, the impacts that summertime could have. We hope this booklet helps readers understand the health issues associated with daylight saving.
March 2012 Special Committee on the Daylight-Saving Time System Japan Society of Sleep Research Chair: Kenichi Homma (Hokkaido University)