Ever since Thomas Edison came up with the idea for the light bulb, people have been trying to improve on the concept. Full spectrum light bulbs represent one of the most significant improvements to date. Light has many different characteristics, and different types of light sources may be more useful or preferable to different situations.

Full spectrum lighting is actually a marketing term. It has no precise scientific definition, but generally describes full spectrum light bulbs that produce light that has certain desirable qualities that make it similar to natural sunlight. Like natural daylight, full spectrum light bulbs produce light that is seen by the human eye in a bluish white tint. The brightness value of the light is similar to that of daylight, and the bulbs have excellent color rendering capability.

Full spectrum light bulbs, since they mimic the qualities of natural sunlight, are very appropriate for individuals who suffer from Seasonal Affective Syndrome (SAD). Natural daylight has always had desirable qualities, and is often recommended for improving mood and motivation. Most people will agree, working in an office with no windows can be depressing. The cold winter months and overcast seasons can also be gloomy, but full spectrum light bulbs can make the indoors look like the height of summer.

There are several types of full spectrum light bulbs. In general, bulbs with color temperatures of 5000K or more produce light that is similar to daytime sunlight. Standard incandescent bulbs coated with neodymium are sometimes marketed under this term, although they do not have the 5000K color temperature. However, they also have desirable qualities, and are able to filter out the harsh yellow tint that is common in standard incandescent bulbs.

The Color Rendering Index (CRI) is a measure used by the lighting industry to indicate a bulb's ability to render colors in objects. It's why some objects look brighter in different types of lighting. The natural sun of course, produces the full spectrum, which is why we see rainbows in the sky. Bulbs with an index rating of 90 to 100 are best at simulating the quality of light produced by the sun. A light source's color temperature is another characteristic, which describes the color of the light that comes from the source.

Full spectrum light bulbs are said to not only improve mood, but also energy, learning ability, and behavior.

Inexpensive bulbs marketed as "cool white" bulbs typically have a low CRI and color temperature, and can cause eye strain. The cool white bulbs do not have the same desirable qualities as true full spectrum light bulbs that provide more natural colors.