Why circadian-friendly lighting for health and well-being has yet to catch on in Singapore

In Singapore, avoiding the sun has become second nature.

People spend much of the day hiding from the heat in shaded and air-conditioned rooms, the curtains, blinds and windows tightly shut. This means less of the natural light that helps regulate the body’s biological clocks.

And local lighting designer Toh Yah Li says most homes and businesses compound the problem with artificial lighting that stays bright, cool and unchanging throughout the day.

An architect by training, she is the founder of Light Collab, a Singapore-based lighting design practice that takes the impact of light on health seriously.

The problem with most LED lighting is “you can’t tune it, and it remains consistent throughout the day”, says the 46-year-old.

But that is not how sunlight works – and it is not ideal for sleep and overall well-being.

The light environment should mimic daylight, “which goes from low in the morning to a peak in the afternoon, then dims before sunset”, says Toh, who in 2015 was one of the first five people to be named a Certified Lighting Designer, the first evidence-based certification in architectural lighting design.

“The colour temperature also changes, and we feel more relaxed with warmer colours and more activated with cooler ones.”

Circadian-friendly lighting

In the last decade, architects and designers in Europe and the United States have warmed to the idea of circadian-friendly lighting – systems and designs that maximise natural light, or use artificial lighting to mimic it.

Lighting designed with these principles in mind is “really good for those who work in shifts and have no access to daylight, such as in basements or retail spaces”, Toh says.

“They are always in the same light environment, so they are affected by sleep disorders because the body loses track of time.”

But she says this design trend has yet to catch on in Singapore, where the widespread adoption of LED bulbs since 2023 has led to many homes and public spaces being lit with LEDs of uniform and unchanging brightness.

And sleep quality is often the first casualty.

The use of bright, blue wavelength-rich lights in the evening or at night tells the body that it is midday when it should be winding down.

“Just like we shouldn’t be taking caffeine at night, we shouldn’t be exposing ourselves to that kind of light after sunset,” Toh says.

But many Singaporeans think bright, cool white lighting is best.

Toh says: “A lot of people have that misconception, especially in Asia. All the aunties and uncles will say, ‘Oh, I’m used to bright and white lights because that’s how I can see.’

“But I worry about their health. And the older folks who tell me that are often the ones with insomnia.”

The lighting in hospitals and nursing homes is particularly bad in this regard.

When Toh’s firm proposed a more circadian-friendly lighting solution for a Singapore nursing home, it encountered strong resistance due to cost and concerns about extra maintenance.

“They are not open to these things,” she says.

Brighter is not better

When designing for clients, Toh looks to the WELL Building Standard, an international certification system for healthier buildings.

She has incorporated its guidelines into various projects, including one for real estate company Singapore Land Group, whose offices she helped redesign.

For home owners and small businesses, however, improving the light environment does not have to mean an expensive overhaul.

During the day, especially in workplaces, Toh recommends light bulbs with a colour temperature of about 4000K, often called “cool white”.

Many people assume brighter is better, but she says there is little need to go above 4000K.

After the sun goes down, the goal is to help the body prepare for sleep. So avoid cool white overhead lighting at this time, and opt instead for warmer bulbs – no more than 3000K.

The physical placement of lights is also critical and often overlooked: Evening lighting should be “positioned lower, below eye level, and not overhead”, she says.

And all light fixtures should ideally be tunable, letting users adjust both colour temperature and brightness.

Toh is a strong advocate of indirect lighting, where the light source is concealed – for example, behind a cove – and illuminates a room by reflecting off walls and ceilings. “It creates fewer shadows and feels much more welcoming.”

Ironically, environmental standards often penalise indirect lighting owing to minor energy losses.

“Because indirect lighting relies on light bouncing off a wall, you lose some efficiency. If you just have a light shining directly down on you, it scores better on paper.”

The issue with such guidelines is that “they are not looking at the quality of light – they are only focused on using as little energy as possible”, says Toh.

But fixating on power-saving above all else is not always the best for health. “And these spaces can become gloomy and uninspiring.”