It turns out stress turning your hair grey isn’t just an old wives’ tale. Acute stress can indeed make your hair turn white prematurely, shows new research. So unless you’re ready to embrace silver strands, it might be worth focusing on lowering your stress levels.

Experiments on mice have revealed that extreme levels of stress causes the sympathetic nervous system to become hyperactive. This causes the rapid deletion of the cells responsible for hair colour, leading to grey or white hair.

The team behind the research says the findings contradict previous theories that stress-related grey hair is a result of immune attacks. Researchers at Harvard were studying the effects of pain on mice by injecting a toxin called resiniferatoxin, when they discovered the rodents’ fur had turned white in four weeks. This prompted them to collaborate with scientists around the world to investigate the biological mechanism that led to the drastic change in the rodents’ hair colour.

The researchers exposed the animals to various types of stressors, including pain, restraint and psychological stress, during different phases of hair growth. Each stressor was found to cause depletion of MeSCs, eventually leading to the development of patches of white hair.

Hair colour is determined by cells called melanocytes, which are derived from melanocyte stem cells (MeSCs). As people age, the supply of MeSCs is gradually depleted, causing coloured hair to be replaced with white hair. But in this case, stress brought on this process early.

On further investigation, the authors found that stress activated the sympathetic nervous system, triggering the release of a neurotransmitter called noradrenaline. They found that noradrenaline caused MeSCs to eventually ‘move away’ from the hair follicles, thereby leading to loss of colour.

The team then looked for genes whose expression was most altered during the stress experiments and narrowed it down to one that encodes a protein called CDK. When mice were injected with a drug that stops the encoding of CDK, the researchers found it prevented fur colour loss.