Hi

A light box bulb apparently should have 10000 lux of full spectrum light. An ordinary bulb is not sufficient. Any SAD light product should come with the appropriate bulb! Also. I was advised to take Vitamin D supplement in the low sun months. I take 4000I.U from late September to January.

Hers a review of SAD bulbs and what is needed:
http://www.essortment.com/light-bulb-reviews-full-spectrum-light-bulb-effectiveness-12688.html
I am not associated with Amazon but here are a range of products to give you an idea: (if this is considered bad form, I apologize -there are many other sellers)
http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Daps&field-
keywords=SAD+lights

Cheers