Why do we think candlelight is romantic?

When it gets dark outside, many people like to light candles. Oliver Stefani, 50, explains why this is the case and what candles have to do with winter 2020. He conducts research at the Center for Chronobiology at the University of Basel, focusing on basic research on the effects of light on people and the perceived quality of light.

SZ: Romantic dinners, birthday cakes, Advent wreaths - when we light candles, it's something special. Why actually?

Oliver Stefani: Candles are extraordinary lighting. One could say: we no longer need them and that is precisely why we need them. This has actually been the case since the invention of the light bulb at the end of the 19th century. Today candles are no longer an instrument of illumination, but rather bearers of meaning, symbols. And there is nothing that can completely replace it.

As a light researcher, you deal scientifically with candlelight. What is different about it than about other light sources?

Candles are actually heat emitters that give off a bit of light as a waste product. Most of the energy produced by burning is thermal energy. The light that candles produce has a very characteristic color spectrum: very few blue components, very high red components. Put simply, this means: the higher the proportion of blue light, the brighter, more like daylight, the light. Activating lighting like we need in the morning has short-wave components of cool white light with a color temperature of over 6000 Kelvin. In contrast, a candle is around 1700 Kelvin, so that is a warmer light color. We perceive this as a softer light. This ensures better production of the hormone melatonin, which helps us fall asleep.

What does the candlelight do to the viewer?

In terms of effect, you could say it like this: light with a high proportion of blue, such as an LED lamp, corresponds to an espresso, it wakes us up. Light with a very low proportion of blue, such as candlelight, acts more like a calming tea. It signals to us: time to rest, relax. Ultimately, it is the small amount of blue that makes candlelight so attractive to us humans, perfect for the evening, when the internal clock allows people to rest. But it is not the light color alone that makes candles so attractive to us.

What is it then?

There is a lot more to it: the slight flickering of the flame, the smell of the burnt wax and, above all, the infrared radiation, i.e. the warmth that the candle generates. All of this creates feelings of security and calm. In contrast to LEDs, we can look into the flame without being dazzled.

Can you imitate a candle?

Limited. It is already possible to emulate the light of candles to a large extent with LEDs. Sometimes this is deceptively real when the light color, the amount of light and the dynamics, i.e. the flickering of the candle in an imaginary breeze, are right. But still, people still perceive it as an imitation. The psychological effect has not yet been replicable. After all, lighting researchers and lighting experts have been trying to fathom this magic for decades - but it has not yet been 100 percent successful.

What are the psychological effects?

As a light researcher, I'm not a specialist, but there are studies that show that light like that of candles stimulates creativity and also encourages exchange with other people. The warmer and dimmed the light, the more likely it is that it is conversations that enable mutual trust and confidence. Ultimately, candles are like tiny campfires around which we like to gather and socialize in a manageable room or listen to stories. The light of a flame has always symbolized protection and security. It reduces fear of the surrounding darkness. Almost no religion does without candles as a means of focusing and self-immersion, as a symbol of hope. Candles form small islands of light in the room that magically attract us.

Do we now, in the first Corona Advent, need candles more than usual?

I think that in a time of uncertainty everything that conveys security and security is an advantage. Especially around Christmas, during the darkest time of the year. That is why candles have this special meaning even in winter. The mild light of the candle caresses our souls. That and the smell, the warmth, awaken memories and old feelings in us. In the candlelight it is certainly easier for many people to get the mixture that so many need now: the memory of better times and the hope of getting better.