Light up the country in a more natural hue of warm yellow-white light.

Dr Tan Wu Meng (Jurong GRC) made this proposal during his adjournment motion at yesterday's Parliament sitting.

He suggested standardising the use of warmer-hued light-emitting diodes (LEDs), rather than pure white ones, in Housing Board estates, roads and schools.

Besides providing a more natural look, the warmer lighting could reduce exposure to blue light - a component of light that some studies have suggested can affect the body's production of the hormone melatonin, which helps to regulate the sleeping-waking cycle, he said.

"There is emerging evidence that by choosing a better way to colour the night, we can reduce the risk of casting a shadow on our sleep and our health," he said, citing policy recommendations in Switzerland and the United States.

"May we choose well and always seek the right kind of illumination," he added.

In response, Senior Minister of State for National Development Desmond Lee said the light colours of HDB common areas and street lamps are carefully selected to meet functional, safety and aesthetic needs.

He said light fittings at new HDB common areas, such as corridors, use pure white light as previous feedback from residents was that warm white was too dim. HDB will study Dr Tan's suggestion to vary lighting levels based on different colours of LED lights, he said.

For road safety, the Land Transport Authority will continue to use pure white lighting for expressways and major arterial roads as this provides higher colour contrast, he added.

But it will study if it is feasible to use warm white lighting for street lamps on minor roads, especially those in residential areas, as these use high-intensity lighting.