Can hair turn white from fright?

Maybe, under the right conditions, but not for most people—and not overnight.

When we’re talking about the effect of fear on the human body, we’re really talking about stress, and stress can certainly cause profound physiological changes. One study also found that hormones created by stress can disrupt the process of cells called melanocytes, which produce pigment for hair and skin. Stress can cause hair loss in several ways; most commonly, it can prompt hair follicles to stay in a resting phase, which causes them to eventually fall out.

Stress might also prompt the onset of an autoimmune disorder like alopecia areata, which causes the body’s immune system to attack pigmented hair follicles. So if a person has a large amount of non-pigmented hair follicles, their hair might appear to "go white" in an extremely short period of time.

&quo;If someone has salt-and-pepper hair—a mixture of gray and black—and they develop alopecia areata, the dark hairs can fall out quickly," David Orentreich, associate director of the Orentreich Medical Group in New York and assistant clinical professor in the department of dermatology at Mount Sinai School of Medicine, told NBC News. "So it appears that they’ve gone gray overnight."

There are historical legends of this effect. For instance, the hair of Queen Marie Antoinette of France allegedly turned white the night before she went to the guillotine. She was only 37 years old when she lost her life. Likewise, Saint Thomas More reportedly went gray while awaiting his execution. It’s possible that their unfortunate situations prompted a bout of alopecia areata.

Some dermatologists refer to a sudden onset of alopecia areata as "Marie Antoinette syndrome" for this reason, but remember, anecdotes of these types of medical events are rarely perfect. Say, for example, that a French peasant had only seen paintings of Marie Antoinette; when he saw her in person, he might note that her hair had "turned white overnight," when, in fact, he had an inaccurate frame of reference. Maybe the sunlight hit Thomas More’s head the wrong way before his execution, or maybe his hair went gray after several weeks—we simply don't know.

Historical accounts of hair "going white" are most likely exaggerations. If hair could turn white from fright overnight, we’d have plenty of case studies documenting the phenomenon. When hair does fall out due to stress, it’s typically due to prolonged stress, not a sudden shock to the system, and it can sometimes return when the stressors have been removed.

In other words, if you’re worried about losing your hair (or your hair color) after watching a scary movie, relax—you’re not going to "go white with fear."