Hong Kong is one of the world's worst cities for light pollution with night skies around 1,000 times brighter than globally accepted levels, researchers said Wednesday ahead of this year's Earth Hour event.

A study by Hong Kong University found that brightness levels in the southern Chinese city's popular shopping district of Tsim Sha Tsui were 1,200 times greater than the international dark sky standard -- a measurement void of manmade light.

The densely-populated city of seven million inhabitants, full of residential highrises, towering office blocks and neon advertisements, has no laws to control external lighting.

The result, researchers say, is that light pollution is thought to be much worse than in other large cities, including London, Sydney, Tokyo and Shanghai.

"In Hong Kong, you cannot go anywhere outdoor in the evening without your eyes being blinded by this really intrusive outdoor lighting," the light pollution survey's head Jason Pun told AFP.

"The fact that we have all this light in the sky means energy is wasted," he said, adding that excessive artificial lighting also adversely affects nocturnal wildlife.

"We should reduce the amount of lighting used and adjust it for the sake of the environment."

Research has suggested that light pollution can cause a number of adverse health effects in humans, including insomnia and headaches, and can also disrupt body clocks and hormones.

The university survey, the result of five million measurements taken from points across the city, was released just days before the start of the annual Earth Hour event, organised by the World Wildlife Fund.

People around the world will be encouraged to turn off their lights for an hour on Saturday night to raise awareness of climate change.

Last year a number of Hong Kong's major buildings along Victoria Harbour, including the International Finance Centre and Central Plaza, went dark to mark Earth Hour.

In France, from July 1 offices and shops will be required to turn their lights off overnight under new light pollution laws.