© (c) Lech Zürs Tourismus by Florian Holzherr
The Skyspace Lech by the American artist James Turrell: An underground color-light space at an altitude of 1780 meters unites art and nature.
December 15, 2025
Christine Bürg
How light affects our mood, internal clock, and health – from winter depression to light therapy to the ideal lighting in everyday life.
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Even single-celled organisms, the smallest forms of life, strive for it. Plants turn their flowers and leaves towards it. And for humans, it is one of the most important basic foods for the psyche and biorhythm. It makes us happy and cheerful, calms us down and builds us up, but it can also stress us, make us sad and tired – especially when it is absent or in short supply.
How important light is for our well-being becomes especially apparent when it is lacking – in the dark season or when the sky is overcast for days or even weeks. About 20 percent of people in Germany feel down due to this lack of light: they become melancholy and withdraw.
Paired with listlessness, chronic fatigue, and exhaustion, these are typical signs of a “Seasonal Affective Disorder” (SAD), the so-called winter depression. It occurs in about two percent of the population. As it is a form of depression it should also be treated by a doctor – supported by light therapy.
Even some blind people feel that light has a positive effect on the body and psyche. Despite the non-functioning cones and rods in the eye, through which we perceive light stimuli and the brain is supplied with information about brightness, darkness, and colors, their internal clock adapts to the natural light-dark rhythm. Researchers from the Salk Institute for Biological Studies in San Diego assume that the affected individuals can sense the light.
This phenomenon is known to anyone who has ever been in a Ganzfeld by the US artist James Turrell. An entirely empty room slowly flooded with changing colored light. Visitors describe a feeling of disorientation and a strange floating state. Turrell himself calls this experience "feeling with the eyes."
All over the world, he makes rooms glow and brings the sky to earth with his Skyspaces. How overwhelming and magical his light installations are can be experienced, for example, in the Skyspace Lech on the Tanegg (skyspace-lech.com) and since last year also in the Freising Diocesan Museum (dimu-freising.de) experience.
© (c) Lech Zürs Tourismus by Florian Holzherr
The Skyspace Lech is open all year round.
Actually, it is Eye one of the best and longest-researched organs. How vision works with rods and cones has been known for more than 170 years. But it was only in the early 2000s that the scientific exploration of the quoted feeling with the eye began.
For a long time, there was a suspicion that there had to be more receptors in the retina. The American neurobiologist George Brainard started it all with the discovery of ganglion cells that react particularly to light with a high blue content. The American neuroscientist David M. Berson finally found the light-sensitive pigment melanopsin in these cells.
In a way, the missing link for biochemical reactions of the human body to visual stimuli. This protein basically acts as an on/off switch for our internal clock. It starts and lowers hormone production, thus also regulating heart rate, breathing, and body temperature. When it detects blue light, the typical daylight frequency, the release of the sleep hormone melatonin is stopped.
This discovery has led to new developments in various fields in recent years – from sleep research in medicine to the lighting industry, which has taken advantage of the blue light findings.
There are spaces where we spontaneously feel comfortable and others that trigger unpleasant feelings in us. Light or lighting can be a decisive factor here. Because: Brightness alone does not make you happy, the change between light and shadow is more important. If a room is completely illuminated, the contrasts are missing. Unconsciously, a feeling of oppression sets in. What does this mean for lighting design – how is feel-good light created?
Ideally through a mix of spotlights, indirect lighting, and light islands that create light and shadow as well as add structure and depth. That's why every room needs different light sources. In the dining area, for example, one or more lights above the table, adjustable floor lamps, as well as ceiling spotlights or uplighters.
Moreover, the light should be focused and not diffuse, like that from lamps with frosted glass. Colors thus appear more vivid and are as brilliant as in sunlight. For the feel-good effect, it is also important not to look into darkness. This means that everything in the field of view – this can also be the hallway, for example, when sitting at the table – should be illuminated.
© Kat Smith
Light has an extreme impact on our well-being.
Everyone knows this from traffic: When we are dazzled, we find it unpleasant, become tired and unfocused over time. That's why lamps, whose light we look into, have no place in the home or office. While focused light is ideal at the dining area because it sets the meal perfectly in scene, the desk should be bathed in light that evenly illuminates the table and casts no shadows.
In both cases, indirect room lighting that brightens the ceiling or wall in spots creates atmosphere. Lighting designers swear by dimmable lights, whose lighting can be adjusted to the time of day and as needed. In the morning, for example, or when we want to be active, we need brighter light, while with a lower amount of light, we automatically switch to rest or relaxation mode.
The light or color temperature is also crucial, measured in Kelvin (K). As a guideline: The higher the Kelvin number, the more bluish and thus colder the light. Daylight corresponds to 5,000 Kelvin (or more) and is used, among other things, for light therapy.
So-called cool white (3,500 to 5,000 Kelvin) is close to morning sunlight and is often used in offices because it enhances alertness and concentration; in the home office, however, 3,000 Kelvin is usually sufficient. For living or dining rooms, warm white, inviting, and relaxing light of 2,700 Kelvin or less is ideal.
Light is our internal clock. When it gets light in the morning, the light-sensitive cells in the retina signal the brain to release less melatonin (also known as the sleep hormone). If we are exposed to artificial light at night (because we work regularly) or if daylight is missing in winter, the sleep-wake rhythm becomes disrupted.
The result: You constantly feel tired, often lacking drive. And this is exactly where light therapy comes in. With so-called light lamps, the lack of (sun)light is supposed to be compensated for. The devices emit very bright, white light, about 100 times stronger than a conventional light bulb. With 6,500 Kelvin and a strength of about 10,000 lux, it corresponds to natural daylight.
People suffering from an autumn-winter depression are recommended a 30-minute light shower to support therapy. Directly after waking up, it should stop the release of melatonin and boost the production of serotonin – the hormone that triggers feelings of happiness and lifts the mood.
In more than half of the patients, a positive effect is noticeable after two to five days, lasting about a week. Nevertheless, scientists are divided on whether or to what extent light therapy helps to brighten the mood. However, they all agree it certainly does no harm.
