In reply to 01wills: Difficult to say.
The dry eyes and throat could be a cold/infection coming on. Could be a change in relative humidity and temperature since the window went in.
First thing I think is the plaster will have gone on wet and will be drying so it is not extracting moisture.
The window, itself, could be giving a better seal so reduced air flow. Also better heat retention so no moisture build up (ie did your previous windows have build up on them?).
Daft one - was the bed moved when the window went in? Could there be plaster on the pillow/bedding/frame that gets disturbed when you sleep?
If the plaster is on the wall and is not touched I cannot see how it would be able to do anything.