This book is a revelation. I knew about SAD already, and that more light helped to lift it, but to combine that idea with exercise just about anyone can do and find time for, then to add a limited cocktail of vitamins to the recipe - clinically tested, both individually and together - gives a dish that's easy to take and (so far at least!) seems to have the effect intended. I have to be the laziest person alive, or nearly, but even I am enjoying my 20 minute walks in daylight.
They are careful to warn about overdosing on the vitamins and that is very clearly presented.
The science is all there if you're interested, but you don't need to read it to realise that the idea makes sense, and even if you don't see the excellent results the book promises, nothing in it should do anyone any harm.
If the results prove to be even half of what the book says they could be, I shall be very happy with my purchase.