I used/use one and find it very helpful. Mine is packed away so I'm sorry but I can't tell you the make. There is a website for SAD www.sad.org.uk which has information on recommended manufacturers.
I think you have to experiment to find out how in front of the light suits you. It can be anything from 30 mins to over an hour I think. You don't have to stare at it though, it just has to be positioned so the light strikes your eye. I put mine by and to the side of my computer monitor and that works fine.
Best of luck.
Does anyone use the Eco wash function on their dishwasher?
World Class Museums - why are they free to everyone?

