We often think about light in terms of warmth or brightness—but there's a measurable quality to light that plays a much deeper role in our health: lux. Lux is a unit that measures light intensity, and it directly influences everything from our energy and mood to hormones, sleep, and metabolism. In a world where we spend most of our time indoors, understanding lux can help us reconnect with a more natural rhythm and support our physiological needs. Here's a simple breakdown of why lux matters—and how to get more of the right kind of light in your daily life.