Stress can affect the body in many ways including insomnia, headaches, muscle tension and even dandruff. While the stress itself is not directly to blame for the dandruff, the true culprit is a microbe on your scalp called Malassezia Globosa. Stress can influence hormone levels, which in some people can affect sebum production on the scalp. Higher amounts of sebum production create a more conducive environment for malassezia to grow and flourish. To help with the pesky flakes, consider swapping your normal shampoo for a dandruff-treating one. Learn more about stress dandruff.