We have just added a new Full Spectrum 45W CFL Light Bulb to our selection, available on Amazon. The color temperature is 5600K, slightly higher than the 5500K model. Both the 5500K & the 5600K are daylight balanced, i.e., they emulate daylight, and are ideal for treatment of S.A.D. or Winter Blues. The difference in color temperature of 100K is not significant if used as a household lamp to help alleviate S.A.D., but if used as a photography light bulb, you want to make sure to chose the one that matches your other lights.
The 45W 5600K Full Spectrum Light Bulbs are available in a pack of 4 on Amazon.
Note: these are large bulbs and they might not fit your standard household lamp; you will need a larger harp to accommodate the bulb and to hold the lamp shade. For bulb dimensions, see diagram. ALZO will offer large harps for the 45W light bulb soon, and it will be announced on this blog.