I wonder if researchers tracked the quantity and quality of sleep (REM vs NREM) among study participants. From the graphs it doesn't look like they did.
So, this wasn't conclusive? Just in case i may walk my dog twice as much but not much can be done with a software engineering job and sedentary hobbies.
There is a pretty large concentration of veins/arteries - 1 that come up around the temple, so that could be related to the frequency of graying starting there.
That's a hugely interesting note there in the introduction.