You should look at the spectral power distribution. CRI (color rendering index) score and CCT (correlated color temperature) are pretty uninformative metrics.<p>The CCT just tells you (approximately) how the relative excitation of short vs. medium&#x2F;long cones in the eye from a particular lamp compares to that of a black body radiator, and the color rendering index tells you how whether a particular set of paint chips looks roughly the same under your lamp as it would look under either daylight or an incandescent bulb (or some value based on linearly interpolating between the two, depending on color temperature). To judge color differences, the CRI takes cone responses and multiplies by a matrix (chromatic adaptation transform), and then uses a standard color difference formula.<p>Most of the so-called “full spectrum lamps” have a spectrum nothing at all like sunlight. It’s not at all clear what kind of spectrum would help fight seasonal depression, but I suspect you want a bit of near ultraviolet radiation, which wouldn’t be measured by either CCT or CRI.