Marina Varlamova, a student from the US, was puzzled by her flat's thick curtains when she came to Hong Kong to study light pollution. She soon figured out their purpose. Used to resting in a pitch-black environment, she and her three companions could hardly sleep because of bright lights outside their Sham Shui Po home. In a survey by the four students from Worcester Polytechnic Institute in Massachusetts, 13 per cent of respondents had considered moving because of lighting outside their homes. Of the 341 people interviewed, 68 per cent wanted lighting in their neighbourhood reduced. Spotlights were blamed for causing the most disturbance - they were given the highest rating, 4.15 out of six, as the perceived source of light pollution. Flashing signs followed with 4.12 points. Respondents reported a medium level of visual fatigue and weariness caused by the lights. To get a sense of how brightly the city is lit, the students took a photometer to the busiest districts. While British agencies recommend that lighting have an intensity of 60 to 100 lux from a distance of 30.5 metres, the four found light from a building in Causeway Bay with various neon signs on its lower floors was as bright as 176 lux. Mong Kok was bathed in lighting of about 150 to 500 lux. Billboard spotlights were about 900 lux. One woman living in Mid-Levels told them: 'It just makes me anxious during the day when it flashes, especially when it is really strong. I don't feel we should be having that sort of flash photography going on in our living room.' Invited by Friends of the Earth to do their research in Hong Kong, the students said they could not have imagined the price residents pay for the city's night scenery. 'I am familiar with all these bright advertising signs and 24-7 cities, being a resident of New York City,' student Michael Ng said. 'However, in New York there are no residential buildings mixed in with these lights, like here in Hong Kong.' There should be shielding regulations in Hong Kong, as there were in most parts of United States, Daniel Karol said. By placing shields at right angles on light sources such as street lamps, light could be focused on specific areas instead of spilling into the surrounding environs, he said. A study on light pollution commissioned by the government is still under way and the Environment Bureau had no comment on that, a spokesman said. It would collect various views and consider the right time to introduce legislation against light pollution.