Snippet from the article:
Can stress really cause hair loss?
Yes. Studies on both laboratory mice and disembodied human hair follicles have shown that external stresses can cause hair loss. Researchers have exposed otherwise healthy mice to mouse-repelling sounds at 15-second intervals for 24 hours. The follicles of the stressed mice went dormant significantly faster than their more relaxed cousins. No such experiment has been conducted on people, but scientists do know that if you expose human hair follicles to substance P, a stress-related neurochemical, they will also become dormant.
Read the rest — Slate: Can Stress Really Make Your Hair Fall Out?
The article references a recent tabloid-style story (in the New York Times) about soon-to-be-former Alaska Governor Sarah Palin’s mystery hair thinning, and wonders if it is due to stress (telogen effluvium), alopecia areata, or genetic hair loss. I haven’t seen the hair loss they’re talking about, but if I had to guess, I’d put my money on it being stress-related.