Once again, daylight saving time is on the front burner — this time as a measure to cope with the anticipated intense daytime heat during the 2020 Tokyo Olympic Games, which will be held in the middle of the summer.

After the organizing committee for the Tokyo Games asked the government for legislative steps to move clocks forward by two hours during the summer season in time for the 2020 Olympics, Prime Minister Shinzo Abe instructed his Liberal Democratic Party to weigh the system, which was temporarily implemented in this country for four years more than six decades ago.

Used in roughly 70 countries around the world today, mainly in Europe and North America, daylight saving time has both benefits and problems.

Proponents say that people starting their work earlier in the day when the air is still cool — and finishing work while there is still plenty of daylight remaining — will save energy in terms of air conditioner and lighting use, and that the added after-work daylight hours will enable people to engage in leisure activities and thus spur more consumption.

Opponents argue that the system would result in company employees working longer hours in the extra daylight hours, which occurred when daylight saving time was introduced right after World War II. There are also worries that moving the clocks twice each year would affect people’s health by disrupting their sleep patterns as they try to adjust.

The system is suddenly back in focus as a possible measure to alleviate the impact of the summer heat on athletes and spectators during the 2020 Games — after the nation was hit by record-breaking heat waves this summer over the same weeks when the capital will host the games in two years — by holding outdoor events such as the marathon even earlier in the morning than is currently planned. But if that is the purpose of adjusting clocks across the country for the summer season, it would be much simpler to just change the start times for Olympic events. Whether introducing daylight saving time is indeed worth the trouble and the cost, including those of adjusting computer systems nationwide to the changed hours, should be carefully examined.

Daylight saving time was last in place in Japan from 1948 to 1951 upon the orders of the Occupation authorities to cut energy consumption in the face of a supply shortage. The measure was abolished when it proved unpopular — it resulted in affecting people’s sleep and getting employees to work longer in the extra daylight hours. Since the 1990s, lawmakers have entertained the idea of reinstalling the system several times, citing possible economic and energy-saving benefits, but each time the discussion went nowhere — as the problems associated with the system appeared to outweigh its touted benefits.

Since the issue was raised only after the heat waves of this summer, there appears to be insufficient time to hold thorough discussions on the matter: Officials say legislative steps for daylight saving time will need to be taken in the Diet this fall if it is to be introduced in time for the 2020 Games. The limited time before the Olympics also means that time will be limited for adjusting computer systems to make the switch to daylight saving time without a hitch, a process deemed to require massive amounts of manpower and money. The question of who would cover these large expenses has not been sorted out.

The benefits that daylight saving time is supposed to bring — to save energy and spur consumption — should also be scrutinized. One of the reasons that the European Union is reviewing the system in place across its members is that it has resulted in only minimal reductions to energy consumption.

Many European countries adopted daylight saving time in the 1970s to conserve electricity by making the best use of the extended daylight during the summer season. The EU rule set in the early 2000s called for moving clocks forward by an hour across the region from late March to late October.

However, the EU is now reportedly contemplating whether to continue with the system in view of growing concern about the detrimental effects of people changing their circadian rhythms twice a year. In soliciting public comments about whether to continue the system, the EU is citing research that the energy-saving effects of daylight saving time are not that large and depend more on geographical factors. Such developments in other countries should also be taken into account as we examine the benefits and costs of introducing daylight saving time in Japan.