Many scientists have investigated whether our hair turns gray due to stress, but despite several promising results they have not yet found a reliable connectivity. Hair color comes from two pigments, called melanin. Eumelanin produces darker shades, from brown to black, and pheomelanin brings brighter shades from blond to reddish. As we age, something interferes with these pigments.
Scientists have two hypotheses: first is that aging damages our DNA which inhibits production of melanocytes – cells that produce melanin. The second hypothesis says hair whitens from the inside thanks to hydrogen peroxide. Our follicles produce hydrogen peroxide in small quantities but it is usually controlled by an enzyme called catalase. A survey conducted in 2009 shows that as we age, the production of catalase is reduced thus releasing hydrogen peroxide and it does its job – whitening hair. This is an interesting hypothesis, but still there is not enough evidence to support it.
Recent studies say that when we are stressed, our body activates the sympathetic nervous system, because of which our heart beats faster, the body is under pressure and the senses are sharpened. This condition is quite bad for the body. One research, conducted in 2011, has showed that the negative effects of constant stress reach to our DNA, which affects genes that control the pigment of the hair. But this is not entirely confirmed.
Although there is no convincing connection, you should avoid stressful situations. The survey of 2011 also revealed that stress is associated with miscarriages, premature aging and various cancers.