How Can Interior Design Relate to the Stars and the Moon?

When walking outdoors at night without artificial lighting, the only sources of illumination are the stars and, if present, the full moon. Until 100–150 years ago, before the widespread use of electricity, people spent their nights under these natural light conditions. Observing this relationship in nature, we realize that nighttime illumination is almost negligible. At night, humans are not exposed to a sun-like brightness, but rather to a level of light barely sufficient to read a piece of paper. For thousands of years, human beings lived their nights in low-light conditions.

So, what can we, as architects, learn from this in terms of interior design?

Stars represent the most fundamental example of a lighting system that illuminates the night without overstimulating the eye.

Today, it is common to see chandeliers positioned above beds and numerous spotlights installed across ceilings in many interior spaces. As architects, we often assume that this approach enhances both the aesthetics and comfort of a space; chandeliers aligned with the bed or the intensive use of spotlights in living rooms are widely accepted as valid design decisions. We tend to believe that the more light a space has at night, the more comfortable it becomes for its users. However, when this assumption is compared with natural nighttime lighting, a clear contradiction emerges.

When a friend who had recently redecorated his home invited me over for advice, I encountered a brightly lit interior filled with dozens of spotlights in the living room and corridors. I suggested that he remove all spotlights and direct light sources and retain only indirect and concealed lighting. He explained that the abundance of light was intended to convey a sense of luxury and expressed surprise at my recommendation. In response, I explained that lighting in nature operates in exactly the opposite way.

Two or three weeks later, he called to tell me that he had removed all the spotlights after our conversation. He added that he now spent more enjoyable evenings with his family and that he was sleeping significantly better.

At night, humans — who are biologically meant to rest after a full day — are reactivated by artificial lighting. A person sitting in a living room illuminated by numerous spotlights and powerful chandeliers is exposed to light levels comparable to daylight. The biological clock, which is activated by sunlight, struggles to shift into rest mode under this artificial daytime effect, disrupting the transition into sleep.

In nature, however, while the sun fully illuminates the world during waking hours, it completely withdraws at night. For this reason, nighttime lighting should rely on indirect and concealed sources that do not directly reach the eye. In residential settings, outside of task-oriented areas such as workspaces, direct lighting is unnecessary during nighttime use. This principle applies not only to homes but to all spaces used at night.

Proper interior lighting should be based on a system in which the light source is not directly visible and the illumination is indirect, evenly distributed throughout the space.

Spending time in dim, indirect lighting allows users to experience the night in a more restful manner and to prepare more naturally for sleep. For humans who have spent thousands of years under starlit skies — without direct exposure to artificial light, and with moonlight reaching the ground only in limited intensity — the most suitable interior lighting follows the same principle.

One of the most common mistakes in bedrooms and hotel rooms is excessive illumination. When a person wakes up at 2 or 3 a.m. and turns on the light, a chandelier above the bed or several spotlights can turn even a brief trip for a glass of water into a sleep-disrupting experience. In contrast, indirect and concealed lighting positioned under the bed or beneath side tables provides the most appropriate solution for nighttime use.

Placing a chandelier directly above the bed, even if the design intention is well considered, is problematic from a nighttime usability perspective.

Nighttime lighting either keeps the user in a constant state of alertness — thereby increasing fatigue — or supports a natural transition period before sleep. Achieving this balance is only possible by emulating the principles of natural nighttime lighting.

Like stars, lighting that does not directly confront the eye and does not disturb the human biological rhythm creates the healthiest and most comfortable interior environments. Whether shaped through evolutionary processes or as part of a consciously designed system, the natural day–night cycle demonstrates that minimal nighttime illumination is essential for human biology. As architects, designing interiors with nearly imperceptible levels of light — rather than artificially recreating daylight — offers the most accurate solution in terms of both comfort and user well-being.