The indoor generation:
chronic light malnutrition

Our ancestors spent millions of years under the open sky. In just a few generations we moved indoors — and our body hasn't caught up. Scientists talk about the "indoor generation": people who spend most of their waking hours cut off from the one light source they evolved for.

Surveys across developed countries repeatedly show that the average person spends 90% or more of the day indoors — in a flat, an office, a car, a shop. The rest is often under an overcast sky or behind glass. It sounds harmless. Biologically, it is one of the biggest environmental changes our species has undergone in the last century.

Why it matters

Light isn't only about seeing. It is a biological signal. Through the eyes and the skin it governs hormone production, the timing of sleep, immune function and even how much energy our cells can make. The sun emits a continuous spectrum — from ultraviolet through visible to infrared, which makes up more than half of the energy reaching the ground.

Artificial lighting mimics this signal only very crudely. Ordinary LED bulbs emit a narrow band with a high proportion of blue and almost no infrared or ultraviolet. During the day they don't reach a fraction of outdoor intensity; in the evening they flood us with blue that tells the body "it's noon".

A window is not the answer

The natural response is: "but I have a window by my desk". Yet ordinary window glass acts as a filter. It blocks practically 100% of UVB — the very wavelength the skin needs to make vitamin D — and significantly weakens other biologically important wavelengths too. Sitting by a window all day is not the same as being outside.

The consequences of light malnutrition

When the body lacks a full light signal for a long time, it shows on several levels at once:

• Vitamin D deficiency — common especially in winter and among people who work indoors, affecting bones, immunity and mood.
• Disrupted sleep — too little daylight and too much evening blue upsets melatonin and shifts the internal clock.
• Lower energy and mood — seasonal mood dips are largely driven by a lack of light.
• Slower recovery — a body without the infrared spectrum misses one of the stimuli that support cellular energy and healing.

How to reverse the deficit

The best solution is free and it's called the sun: get outside in the morning, take breaks outdoors during the day, keep warm dim light in the evening. But the reality of modern life means many of us simply miss too much of that sun — especially in winter, in the north and when working indoors.

This is where targeted light therapy makes sense. A panel with a full therapeutic spectrum — red, infrared and a controlled UV component — can deliver the very wavelengths modern environments take away. Not as a replacement for being outdoors, but as a supplement for the days when you can't get out.