A few years ago, I was at an accessibility conference where the speaker, who was blind, said: “Try turning off all the lights in this room — see who feels disabled then.” His point was that disabilities are often relative to our environments, and the tools are important in overcoming them. Lighting is a tool we have used for thousands of years, from oil lamps to wooden torches to modern electric lightbulbs.

Our first — perhaps only — desire for lighting is that it improves our visibility in darkness. This is an important priority. But humans are surprisingly adaptive: In a pitch-black room, the light of a single candle will illuminate the space for us. Our eyes adapt from darkness to something-better-than-darkness quite quickly, even if it is far from the ideal degree of visibility.

This is why we often settle for the lighting that comes with a house and, as long as there are lights in each room, we accept this lighting as “good enough.”

We settle for the ceiling pendant original to the kitchen, despite the shadows it casts on the work surface when you stand at the counter. We accept the recessed can lights in the living room despite the harsh glare when you sit on the sofa (or simply avoid the glare by using the television as a sole source of illumination as the night goes on). We choose between the ceiling fan and the recessed lights, for simultaneous use creates a headache-inducing strobe effect.

Even if there is a light in a space, it needs to be judged by its ability to safely illuminate our tasks at hand. In any given room of your home, what activities are taking place? What are the obstacles that may be in the way of that activity or of general egress and traffic flow through the room? All these elements need to be incorporated into an effective lighting design.

Perhaps most important, could you use more light? More homes suffer more from a lack of proper lighting than over-illumination. Poor lighting — especially when accented by harsh, electronic screen lighting — can cause eyestrain and other visual issues, such as fatigue. As we age, our eyes’ ability to detect contrast decreases, so proper lighting becomes especially important as our vision degrades.

Illumination through electricity — especially over the past two decades with electronic screens and the blue light they emit — has brought attention to the impact artificial lighting has on our biological clock. This clock, known as our circadian rhythm, is our natural sleep/wake cycle based on Earth’s 24-hour day/night cycle. Being exposed to blue light (such as from electronics, many LED bulbs or fluorescent bulbs) at night negatively affects this cycle and can lead to health issues. The takeaway from a residential lighting design is to incorporate soft, yellow light into any night-light paths and equally warm lighting for any night lights.