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.
Water shortages and hosepipe bans
Employing a cleaner - and difficulties thereof

