Can stress make your hair go grey?
Our surgeon Asim Shahmalak at Crown Clinic is often asked questions about hair.
One of the most common is: does stress make your hair go grey?
The simple answer to this is: yes.
You only have to look at the experience of some of the most powerful men in the world to see how this is true.
Check out the link below to see how being President of the United States has aged Barack Obama:
Look at pictures of Obama - they show a man a world away from the fresh-faced young victor six years ago.
Obama's hair shows the unrelenting pressure heaped upon the man known as 'Leader of the Free World'.
The President's once dark and closely cropped locks are now streaked with grey and palpably thinning on the crown and around his temples.
Obama, whose youthful bearing and demeanour was a big part of his original sell to voters, admitted recently: 'I'm full of grey hair, but I'm not weary.'
While his crow's feet and greying hair are only the most visible signs of the pressure of his job, it would be a mistake to underestimate their import.
These very visible physical manifestations of stress are not simply a gift to the world's picture editors, and hair transplant surgeons like our own Dr Shahmalak. They are an outward indicator of the internal difficulties of leadership in the modern world.
Obama is not the first powerful man - and it is mainly men affected in this way - whose hair has suffered and signalled the strains of his job.
Tony Blair went into office as Prime Minister with lush brown hair and a sense of tennis-playing energy. Like Obama, his relative youthfulness was part of his sell to British electors who were tired of the grey men of the Conservative party.
After a decade in power, Mr Blair's hair had receded dramatically around the temples and on the crown, and was visibly thinning and streaked with grey.
He looked exhausted.
It was the same story for his successor, Gordon Brown.
Despite being nicknamed the 'Iron Chancellor', he became PM in 2007 with just a few steely streaks in his otherwise raven-dark hair.
By the time he left Downing Street, having gone toe-to-toe with global economic meltdown and a bitter and ultimately fruitless election battle, his hair was streaked in battleship grey.
David Cameron, who was only 43 when he became PM, was showing greying hairs within a few months.
Dr Shahmalak explained this ageing process.
He said: "Human hair becomes grey - then progressively whiter - because ageing naturally lowers the amount of pigmentation in follicles.
"This pigmentation, known as melanin, ceases to be produced by the body in sufficient amounts as we grow older. As this happens, new hairs appear grey, then white.
"But it's not just our age that affects hair colour.
"Family genes and stress - divorce, unemployment, a high-pressure job - can all play a role.
President Obama's job and age - 53 - make him high risk for greying and male pattern baldness. The latter is the main cause of hair loss, affecting an estimated quarter of men by the age of 30 and two thirds by the age of 60.
The bad news for Obama is that when he does retire in another two years - presumably to something less stressful - his hair won't return to its original colour.
Sadly, it's very common for those in high-powered jobs to suffer premature greying.
Stress, and changes in levels of the male hormone testosterone that a high-pressure job with long hours, high anxiety and lack of sleep can engender, play havoc with hair colour and density. In the very worst cases, they can trigger total hair loss, alopecia.
Dr Shahmalak added: "I'm not suggesting the 44th President of the United States needs a hair transplant. His hair loss is mild, but he should look after it. I'd recommend using the drug Propecia to help prevent any further loss of density and a special shampoo to nourish his roots."
In today's society image is vitally important. The fact Obama himself mentioned his greying hair tells us that much.
For the President to project America as ready for the next challenge, with a new sense of energy and urgency, as he has done, it couldn't hurt for him to look and sound a bit more like the youthful Senator from Illinois of six years ago.