It's not the color temperature that determines the efficacy of phototherapy for seasonal depression, but the light intensity, measured in lumens.

There are special high-intensity fluorescent bulbs that meet the requirements, but they do not fit standard fluorescent bulbholders. Not only that, these bulbs emit a fairly significant dose of UV light, and appropriate filters are a necessity. The poster who suggested using tanning bed lights is considering a very dangerous thing indeed. Tanning bed lights work because of the UV output. They are not suitable for phototherapy.

I happen to think that the best product on the market is by Northern Light Technologies, but there are other good products out there. Some general questions are answered in their FAQ. http://www.northernlighttechnologies.com/faq.php

They happen to use a 3000K color temperature, but other bulbs are available that fit the fixture's bulbholders, if a different spectral character is chosen.

Lar