The human eye is a masterpiece of adaptation. It can move through different light levels thanks to two retinal systems that take turns according to the moment: the cones, central to daytime (photopic) vision, let us perceive shapes and colours with precision; and the rods, which take over when light decreases, enabling a gradual adaptation toward darkness.

In real life, however, we rarely let that process unfold naturally. We go from intense outdoor light to overlit interiors — homes, hotels, even offices. And without realizing it, we leave little room for mesopic vision, that intermediate state between light and darkness in which the visual system adjusts, calms and prepares for rest. This adaptation isn’t instantaneous: it can take between 4 and 8 minutes, and depends on retinal metabolism and the coordinated work of cones and rods.

When we let the light dim, especially close to bedtime, the body interprets it as a signal of safety: it favours relaxation, reduces activation and helps the mind enter a calmer state. By contrast, keeping high indoor lighting levels sustains wakefulness and stimulation — a poor companion for recovery.

There’s another key factor: many indoor light sources include wavelengths near the blue, which the eye perceives as more aggressive and which can become undesirable in excess, especially at night. There’s a reason we protect ourselves from the sun with filters and tinted glass: the body knows how to read the spectrum.

From this physiological understanding emerges Kerai’s approach, developed in collaboration with Jordi Saladié and his team: to work with quantitative changes of light and a spectrum designed for night-time wellbeing. We tune light toward orange and amber tones, and use low emission levels to create environments that feel pleasant — enough to move around naturally, without ceasing to respect the visual system.

Lighting that doesn’t just look good — it feels good.

The result is lighting that doesn’t just look good — it feels good. Light that accompanies rather than imposes. A dialogue between aesthetics, material and knowledge of the body.