I've drifted away from many friends over the past few years as I realized I was being someone who isn't myself when I was around certain people... I know it doesn't really qualify as solitude, but not being "on" for a week, then a month, then a year, you really start to know yourself, and begin tracing unhealthy thought patterns back to some of the people who helped to imprint them on you (including yourself).
Glad I found this thread, made me reflect on that period of time.