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By Kaori Kaneko and Elaine Lies
TOKYO, Aug 6 (Reuters) - Enduring a deadly heatwave this summer, Japan is considering adopting daylight saving time from next year, so that the 2020 Tokyo Olympic Games can stage events during cooler hours, the Sankei Shimbun newspaper reported on Monday.
The report prompted an outpouring of opposition on social media from people worried that it would result in longer hours at work, and the main government spokesman said a decision had still to be taken.
"It is not true that the government has decided to aim for adopting daylight savings time," Chief Cabinet Secretary Yoshihide Suga told a news conference said, citing a "major" impact on peoples' lives.
"We plan broad measures such as earlier start times, more greenery and heat-inhibiting pavements."
At least 120 people died during the scorching heat this summer, raising concerns about athletes' safety during the 2020 Games, which will be held in late July and early August, Japan's hottest, most humid months.
Tokyo 2020 Olympics President Yoshiro Mori had previously requested Japan's Prime Minister Shinzo Abe to adopt daylight saving time as it would allow events scheduled for the morning, such as the marathon, to be held during cooler hours.
Citing several sources, the Sankei Shimbun report said the government was considering bringing clocks forward by two hours between June and August next year on a trial basis, to iron out any problems with the change, ahead of a similar implementation during the Olympics.
Pressing the case for a switch to daylight savings, Masa Takaya, Tokyo 2020 spokesman, said in a statement that the step would "also help protect the environment and realise a low-carbon society in Japan."
Japan is among a handful of major economies that does not use daylight saving time during the summer, including South Korea - which set clocks back an hour in 1987 and 1988, when it hosted the Summer Olympics in Seoul.
Japan had daylight saving from 1948 to 1952 under the U.S. Occupation - a bitter memory experts say coloured discussions about the measure in the 1970s and early 2000s as an energy-saving step.
Popular fears were that peer pressure about leaving work during daylight would keep workers at it longer.
"Things are completely different, companies are now trying to limit working hours," said Hidetoshi Nakagami, head of the energy think-tank Jyunkankyo Research Institute.
"Data does show working hours did rise then, but you have to consider historical context - productivity was booming."
Economists said measure's impact on behaviour could be mixed.
"If people start working two hours early and finish two hours early, consumer spending is expected to rise," said Toshihiro Nagahama, executive chief economist at Dai-ichi Life Research Institute.
"But given the labour shortage, the end of working time may not change and people may still work longer hours."
That was the biggest fear on social media, where the topic was one of Monday's hottest and worries ranged from having to reprogram computers to losing sleep.
"It's way too easy to imagine that we'll start work two hours earlier and finish the same at dark, meaning bastardly long days," wrote one.
That happened in Seoul, according to the National Archives. People complained that the longer days were hard to adjust to, and the sense that this was done to coordinate with foreign television stations left a bad taste for many. Accordingly, it was scrapped after 1988. (Additional reporting by Jeongmin Kim in SEOUL; Editing by Simon Cameron-Moore)