Hi tiredemma
People are right - whatever you do has to be quite carefully chosen (I have a BA (Hons) in Social Studies, and went on to do post-grad nurse training).
Whatever you do has to:
-Be big enough that there is lots of material out there for your literature review - nothing worse than having 2 sources to inform your study!
-Be on a topic that will have an 'angle' that isn't completely run of the mill. - No good concluding that "depressed people can struggle to stay positive" IYSWIM - you need to be able to draw something a little bit new.
-Be specific enough that you don't need to review every issue within mental health nursing.
-Be interesting enough to you to sustain months of reading, exploring, and writing.
If I was you, I would think that something like:
"With a changing society, a move away from the extended family to the nuclear family, and the availability of the internet, is there a place for online mental health support services for people experiencing ?"
With permission of MNHQ, you would have a cracking source of the practical workings of peer support (i.e. MN) and then you could extrapolate that to a group or individual support system. Like an online AA, for example.
If I had my time again (did general nursing) and did MH nursing, that's what my dissertation would be!