Kind of a vague question, but I've been led to wonder about it this evening.
My situation: I started a PhD program (humanities) last September. So it's been just a few months, though as with (I assume) many programs, it's quite an intense, immersive experience. I find myself thinking differently, speaking more carefully and more slowly, being less open and more guarded, maybe being less ostensibly friendly (i.e. smiling less, etc), on the whole. Part of the reason I'm surprised by this is that I'm in my late 20s, and had previously thought myself quite 'settled' in myself, as it were.
That might read like a depressing picture, but I don't necessarily regard any of those changes as bad. I'm curious as to whether other people have experienced anything similar. I'm also curious whether one should expect to be changed by a graduate program, whether it's important to hold on to 'yourself', something in between, or what.