Sorry to hear about your trousers Roger. I find the phenomenon to be at it's height shortly after the summer and Christmas holidays, I think that the garments being stationary for a longer period of time seems to act as a catalyst in the whole process. Certainly how it plays out in my place.
I also find that a common side effect of this shrinkage of waistbands is dirty shoes....bear with me....
I've noticed that when I find my clothing to have shrunk inexplicably it more often than not coincides with my usually well polished shoes not being kept to their own high standards....without my noticing. I struggle to explain that why, after my Christmas or summer holidays, I don't tend to notice that my shoes are not as clean as I would normally like. It's almost as if the distress over the random shrinking of my suits leaves me with a blind spot with regards to my shoe care.
If anyone can offer a scientific explanation to this secondary condition it would be appreciated as I find the whole situation most unsettling.
M
Very observant - I rarely am able to see my shoes after the holidays so perhaps your condition is still in it's early stages. I am guessing the oils, waxes and various chemicals used to keep your shoes in pristine condition may emit chemicals which migrate up your trouser leg and then as they exit out the top waistband the re-combination with the ambient air induces a chemical reaction which causes the fibers of the waistband to shrink. As the chemicals leave your shoes they become dirtier while the waist of your trousers become tighter. Residual fumes may also affect the lower parts of your shirts, jackets, etc also causing them to shrink and feel a little tighter around your middle.
.........just a theory ............
DE