Can Fight or Flight Turn hair White? 

By Bruce Veloso

An old tale going back to the 1789-1799 French revolution says that Marie Antoinette, the last queen of France, was sentenced to the guillotine after being accused of treason, it is said that her hair turned white overnight. It is believed that the stress caused by being sentenced to death resulted in the change of Marie’s hair color.  Although the story may seem farfetched, research suggests that high levels of stress can indeed change the hair to a white color.

Recently, a team of researchers led by Bing Zhang from the Harvard University Stem cell institute, identified a mechanism that links hyperactivation of the sympathetic nervous system and a rise in norepinephrine to a reduction of stem cells that specifically regenerate pigment in the hair follicles of mice. It was clearly noted this linkage turns hair white¹.

For the longest time it’s been said that stress makes the hair turn white, but until now there was no scientific basis for this belief. Our study proved that the phenomenon does indeed occur, and we identified the mechanisms involved. In addition, we discovered a way of interrupting the process of hair color loss due to stress” 

Co-author, Thiago Mattar Cunha. 

When the researchers involved in this study first tried to figure out why acute stress can cause gray hair, the stress hormone cortisol was expected to be the main causative factor for the loss of hair colour, because stress elevates levels of the hormone cortisol in the body. But it came as a surprise to the researchers that once the adrenal gland from the mice was removed so that they could not produce cortisol, the hair still turned grey under stress. This suggested that cortisol was not a main causative factor in the hair turning gray.

Figure 1. Stress turns hair white: Comparison of representative control mouse with black fur (left) to a representative mouse subject to sustained stress for several months (right)1

How does stress change hair color? 

When the researchers involved in this study first tried to figure out why acute stress can cause gray hair, the stress hormone cortisol was expected to be the main causative factor for the loss of hair color, because stress elevates levels of the hormone cortisol in the body. But it came as a surprise to the researchers that once the adrenal gland from the mice was removed, so that they could not produce cortisol, the hair still turned grey under stress. This suggested that cortisol was not a main causative factor in the hair turning gray. This then led to the researchers to expand the focus of the experiment to the entire sympathetic nervous system (SNS), which directly impacts the fight or flight response in both humans and mice. The experiments involved the use of a dark furred mouse and it was noted that the SNS can touch every mouse hair follicle. When pain-induced stress was applied, it triggered a fight-or-flight response from the mice in the autonomic nervous system that caused a rise in norepinephrine levels. This rise in norepinephrine then disabled the pigment-regeneration ability of the stem cells present in the hair follicle. 

Acute stress, particularly the fight-or-flight response, has been traditionally viewed to be beneficial for an animal’s survival. But in this case, acute stress causes permanent depletion of stem cells.” 

Lead author, Bing Zhang. 

This research paper was widely praised within the scientific community in 2020. The significance of this findings can be expanded past hair follicles and allow scientists globally to better understand how acute stress can impact other tissues and organs within the human body. This, perhaps, allowing for different treatments of known conditions, treatments that can reduce the impact of stress on our bodies. 


1.  Zhang B, Ma S, Rachmin I, et al. Hyperactivation of sympathetic nerves drives depletion of melanocyte stem cells. Nature. 2020;577(7792):676-681. doi:10.1038/s41586-020-1935-3 

Phoenix from the ashes: Lung tissue damaged by tobacco smoking may be able to regenerate

What if lung tissue could regenerate after smoking damage and become healthy again – like a phoenix rising from the ashes? Bruce Veloso discusses surprising new research published by Nature which suggests that this may be the case.

By Bruce Veloso

What if lung tissue could regenerate after smoking damage and become healthy again – like a phoenix rising from the ashes?

Surprising new research published by Nature1 suggests that this may be the case. It has been found that cells which escape damage have the ability to repair smoking-related damage inflicted on other cells in the lungs – but only if you stop smoking.

Hundreds of carcinogens are present in tobacco, which cause changes in DNA sequences of cells, resulting in the formation of cancerous cells over time. For years, it was thought that damage in the lungs caused by smoking was irreversible. and life-long with an unspoken rule which stated that lung cancer was soon to chase after and find ex-smokers. New research suggests that this may not necessarily be true. The results of quitting tobacco cause lungs to self-repair, noted in people who smoked at least a pack of cigarettes continuously for more than 30 years.


– Dr Campbell, of the Wellcome Sanger Institute, involved in the research1

It was also observed that the lungs of past smokers were comparable to people who had never smoked before, because the healthy cells that were able to avoid tobacco-related mutations could replace the damaged cells. It was noted that the majority of cells taken from a smoker’s airway had suffered mutations, with cells displaying up to 10,000 genetic alterations. But to the researchers’ surprise, a few cells managed to avoid damage to their DNA. How exactly, is as yet unknown. Nonetheless, after an individual stops smoking tobacco, those are the cells that repair the lungs by replacing the damaged cells.

Need a reason to quit smoking?

According to this paper, after you quit, your heart rate drops. In less than 12 hours, carbon monoxide level in your blood drops to normal. In 2-12 weeks, your circulation and lung function improve. Within 1-9 months Coughing and shortness of breath decrease. After only 5-15 years, your stroke risk is reduced to that of a non-smoker, lung cancer death rate is about half of a smoker and risk of heart disease is that of a non-smoker. The longer you stay away from tobacco the more your health can improve – quitting can be challenging but it is possible.

NHS Stop Smoking Services are free, local services providing a range of techniques to help you stop smoking. You can gain access to a stop smoking adviser via a GP referral or by contacting an adviser directly. To contact a stop smoking service in England, please call the free smoke-free national helpline: 0300 123 1044


1. Tobacco smoking and somatic mutations in human bronchial epithelium. Yoshida, K., et al. 7794, 2020, Nature, Vol. 578, pp. 266-272. Doi: 10.1038/s41586-020-1961-1.