I do believe the daylight bulbs do not meet the same requirements as full spectrum and it is full spectrum that are beneficial.
I have recently gotten bulbs from
Full Spectrum Lighting and Light Therapy
I really like their bulbs....they are very reasonable as these things go and the CRI on the 13 W is 93 and the K are 5500....The slightly higher wattage bulbs are 94 and 5900....I would probably suggest sticking between 13 and 18/19 W...There is a lot of info out there and it is very confusing....so do your research but you certainly don't need to spend a fortune for the lighting benefits as you can buy bulbs that fit into standard fixtures....
Essentially FSL needs a CRI of 90+ and between 5000-6000 K. That's why I like these fullspectrum solution bulbs. I also like that they are amalgam filled which prevents the mercury from leaking if the bulbs are accidentally broken.
Good luck....