Many thanks for all the good advice. Looks like I am in for a lot more reading. :)
Thank you for the links.
I am sorry to hear that salesmen not to be trusted and I need to be aware of tow ratings independently of what they tell me.
The light therapy involves only natural light, no use of electric light, hopefully syncing with daylight and dark. It is the ambient light from street lights/houses/businesses that need to be avoided and of course no lights on after dark in the house. If it sounds desperate it is! LOL A big reason not to invest much.