The rule of thumb is using lighting reasonably: do not set up unnecessary lighting and turn off lights which are not in use. We are not implying that you should live in the dark, rather just turn off the light when you leave a room can simply achieve the target. Turning off the neon signboards on the streets at midnight, reducing the hours of floodlight on golf courses, road lights in country parks and decorative lights on Tsing Ma Bridge are all possible ways being considered by government and organizations.
Turing off outdoor lightings at mid-night helps in reducing light pollution? If you have experience in star-grazing on Cheung Chau, you may noticed that by turning off the extensive lightings of the football court near Kwun Yam Beach, the strongest light pollution source among the island, at 11pm, many stars and even the Milky Way will emerge out immediately due to the dramatically reduction of light pollution. In 1996 during the brightened of comet Hyakutake, Ministry of the Environment of Government of Japan guided japanese to turn off the lights and so the night sky was 1.5 magnitude dimmer.