It is midnight and the lights in Dorothy Lau's flat at Ho Man Tin are out. Yet, her home is lit up as brightly as it would be on a sunny summer afternoon.
About one kilometre away from her building, two tall floodlights shoot wide, high-intensity beams through her windows.
Several residents in the area have been complaining in recent weeks about the new set of floodlights erected in the sports field at King George V School on Tin Kwong Road. "I have to use two layers of curtains just to be able to sleep," Lau said.
Twelve of the lights were burning in broad daylight last weekend, she said. And on one evening last month, the glare from the lights was so bad that she called the police.
"The police spoke to them, then the lights went off for that night. But then the problem continued," Lau said. "Is there really a need to use the lights in the daytime and at midnight?"
The school's principal, Ed Wickins, responding to inquiries from the South China Morning Post, said there was a problem with the timer on the lights. He said a refurbishment of the school field was in its final stages, with the new set of "very modern" floodlights being installed and tested.
"The lights' timing device may have malfunctioned. The tests have revealed the problem to the contractor, and the proper adjustments will be made," Wickins said, adding that he was aware of the inconvenience it had caused residents.
The English Schools Foundation school apologised to the community and pledged to resolve any remaining issues.
A study last year found Hong Kong to be the world's worst city for light pollution. Unlike cities such as London and Shanghai, Hong Kong has no laws to control excessive external lighting.
"Police and the [Environmental Protection Department] can only … advise businesses to switch off their lights," Friends of the Earth general affairs director Edwin Lau Che-feng said.
"The government must move to legislate, or there will be no incentives to shut off [external] lighting."
Lau noted that the government had not reported on a public consultation on light pollution that ended in October.
With no light pollution law in place, the department issues a set of "best-practice guidelines" to urge people to minimise light nuisance and energy wastage. These include recommended operating hours.
The department said it received 259 complaints about light nuisance last year.