You could just search for a dry scientific description from the wikipedia that describes the differences between the glow of sources with different color temperatures, but this is unlikely to be informative for our interior design case. In addition, modern lamps and chandeliers, due to their design, shape, color and features of work, have some extent that influenced the terminology when describing the actual light picture. Perhaps the only constant reference point for scientists and just specialists in the field of lighting engineering is the temperature scale, graduated in Kelvin. We propose to consider the ranges in which this or that glow falls.

Warm light lies at the beginning of the scale – usually means a gap between 1000 K and 3500 K. When describing such kind of glow from a lower value to a larger one, an ordinary person will use the words “reddish”, “orange”, “lemon”, “yellow” and “light yellow”. In this range, a fire burns, a match and a candle shine, and it’s an ordinary incandescent bulb lights.

Neutral light is actually a transitional light from warm to cold. Its color temperature range is 3500-6000 K. To describe such glow imagine a white light without clearly distinguishable shades of yellow or bluish tones. The middle part of this interval falls on the radiation of the sun on a fine day: lower color temperatures are conventionally a morning or summer light pattern, and larger ones are pre-twilight time or an autumn day. It is now technologically the easiest to obtain this glow color, and therefore it can be found in halogen, gas-discharge, and LED models. Neutral lights is good for pieces of art in the room. If there is a need to highlight a painting for example, you will probably consider neutral lights, because this way a painting or sculpture would keep their own color structure, galleries prefer neutral picture light too.

Cold light is on the other side of this scale, relative to neutral. Its color temperatures lie in the range of 6000-10000 K. As the value increases, it is described as “sky”, “bluish”, “light blue”, “bluish” and “pronounced blue”. In nature, such a glow is practically not found, but artificially it can be obtained in halogen lamps, and in LED lamps, and using inert gases – argon, neon, xenon, etc.

Attentive readers probably managed to note that the path from warm to cold in numerical terms does not correspond to the usual logic. It must be remembered that a warm glow will have a lower color temperature, and a cold glow will have a higher one. This is due to the very physics of the process, and the use of the scale in its current form is well established, so you just have to always keep this aspect in mind when choosing bulbs by temperature.

 What shade to choose?

On the Internet, you can find a lot of articles whose authors dive too deeply. They write that light bulbs with a cold glow color have a negative effect on the visual system, and models with an overly warm shade increase fatigue. Thus, products with a neutral shade are automatically brought to the fore – as the closest to nature, evolutionarily familiar to humans. In reality, the alignment of forces looks a little different.

From a medical point of view, the human eye is one of the most adaptable organs. It is impossible to spoil your eyesight by reading by the light of a wall lamp with a light bulb of a certain color temperature. But it is very easy to tire your eyes with insufficient illumination received from any lamp. Thus, the more important characteristic is the brightness of the source, rather than its chromaticity. In summary, we can only advise consumers not to read in dim light and not to save energy at the cost of their health, but to always purchase light bulbs with a suitable power for the circumstances. Moreover, modern LED solutions are already extremely economical.

Another issue is the psychological state. This is where the color factor really matters. The environment affects the reaction rate, attention, concentration, sense of space, comfort level and, only as a consequence, the degree of fatigue. Let’s consider all this in a little more detail.

Moderately warm shades usually have a calming effect, but do not completely relax a person, do not incline him to sleep. Cold light, on the contrary, irritates our brain a little – and the longer we stay in such an environment, the more. The neutral-warm shade allows you to relax comfortably without losing control over what is happening, it maintains sufficient brain activity, and therefore muscle tone. Neutral-cold tones perfectly increase concentration, stimulate a person to move, do work, and not sit idle. Just a neutral glow does not have a pronounced effect – at the subconscious level, we perceive it as the light of the sun, which seems completely natural, and therefore is actually leveled. 

Is it possible to say unequivocally that the ideal solution is a neutral day shade? In our opinion, no. Both combinations, transitional states to other coloristic tonesare needed for work and for rest. Perhaps the only conclusion where there is no need to argue is that cold lighting, especially with a high color temperature, does not have a widespread practical application – it is used only for specific tasks. But the rest of the spectrum, from pronounced yellow through warm and neutral to neutral-cold, has the right to be used in everyday life, in production, in office premises, in housing and communal services, in trade and entertainment.

Instead of a conclusion

The endless debate about which shade of glow is best is often shattered by misconceptions about the nature of light. In addition to color temperature and brightness, there are also such characteristics as luminous flux density and illumination, color rendering level and pulsation coefficient, direction, degree of reflection, polarization, etc. All of them are intertwined with each other in different combinations, forming a variety of light patterns. There are those that are ignored by the organs of vision, but are noted by the brain (for example, flicker, which we recently wrote about in a separate article), but there are also those that are almost not important for a person (polarization).

Separately, it is necessary to note the fact that the perception of the light pattern is individual for each person. In an era of a huge variety of models, it is imperative to experiment a little with colors and glow intensity in order to find the most optimal ones for yourself. The popular formula of “neutral light for the living room, warm light for the bedroom, and cool light for the bathroom” is not as universal as it seems. In residential interiors, where there are a lot of cabinets and upholstered furniture, it often makes sense to focus on transitional neutral-warm tones, in the bedroom – simply reduce the power of the sources, and not switch all the chandeliers and sconces to light bulbs with a yellow glow. In addition, even in bathrooms, where there are a lot of already cold ceramic tiles, it often makes sense, on the contrary, to create a warmer atmosphere.