Hi - thanks for your responses (& sorry to hear you have experienced SAD, katymac, though it sounds as though a bit of extra sunlight may be helping you ).
I've heard about those dawn lamps, Mrs Badger, and I quite fancied getting one, although I have heard that they don't have the lux power of the SAD lightboxes themselves - it seems to be the light intensity of full-spectrum light you need to have to activate the anti-depressant response.
To be honest, I'm not sure I actually have SAD, but have been battling with depression on and off for as long as I can remember. Have tried therapy - CBT, Jungian, Freudian, integrated, you name it - as well as acupuncture, ADs (both SSRIs and tricyclics) - to no avail, or at least not for very long. I feel as though things are worse in winter (although that may simply be because it's winter at the moment and I'm feeling a bit rubbish) and would be prepared to give almost anything a shot if I thought there was a cat in hell's chance it might help.
Thanks again, and if anyone has any details about the actual lights themselves, what to look for and where to get hold of them, I'd really really appreciate it.