yeah I've had that happen too, I am on Effexor now as well and it works better than anything else i've tried but I have noticed it seems not to be doing as much as when i first started it.

For seasonal affective disorder I have heard that MAO inhibitors are quite effective. I don't have that myself but a friend of mine had it very severe. She tried ssris, as well as ECT, neither of which helped for more than a few months. then she finally went on an MAOI about a year ago, I forget which one -- she had avoided them before because there are a lot of tricky side effects, but it is still working and she is really doing great.

best of luck
cthonica