Just before leaving for vacation, I had my hair colored and cut for the first time since November. My roots were about five inches long, not a look I recommend, but oh well.
Turns out, half of my hair fell out sometime in the last 8 months, and it started to grow back around May or June. Not bald patches that would mean alopecia, but a mass exodus from my scalp, every other hair (or so) abandoning ship, deciding it would have a better life down the shower drain or in the carpet. "You out of here?"
It might be a thyroid condition, but since it is growing back, it is most likely from stress.