Anyone who has watched a President who isn’t dying their hair through their term in office
knows stress might be a cause for gray hair.
If you have teenagers, you've probably even remarked to them the stress they cause you
is making your hair turn gray, all the while not fully appreciating the fact that you have
hair in the first place....
In any event, the truth is going gray really has to do with the production of pigment in
your hair follicles.
That production process can be altered by several contributing factors, stress being
one of them.
To understand what makes our hair turn gray, we need to first talk about what makes our
hair grow and give it color.
A person's hair color is the result of pigments known as melanin.
Made from two amino acids (tyrosine and phenylalanine), these pigments are produced by a specialized
group of cells known as melanocytes.
They do this through a process called melanogenesis.
Melanocytes are found throughout our body and the melanin they produce is what gives
our skin, hair, and eyes their color.
The melanocytes responsible for hair color are found in the bulbs of your hair follicles.
Even though there is a wide range of hair and skin color, there are only two main types
of melanin- eumelanin is what produces dark browns and blacks, and pheomelanin produces
reddish/yellow.
How these cells blend together will determine what color your hair will be.
It isn't fully known what makes the melanocytes blend together in the ways they do, to make
the specific hair color for each individual.
What is known is that there appears to be clear genetic factors.
One gene, and its alleles responsible for red hair, have already been identified; known
as MC1R, this is also the same gene responsible for red pigments in several other species,
like cows.
Once the specific formulation of melanin is produced, their granules are transferred to
adjacent keratinocytes, also found in the bulbs of your hair follicles.
Keratinocytes are what produce keratine, the dead protein cells that make up our hair.
Once a Keratinocyte undergoes its scheduled death, it retains the melanin making our hair
color what it is.
Gray hair is the result of less melanin within the keratin.
The less melanin, the more gray your hair will be.
White hair has no melanin at all.
There are a few different processes that can make our hair turn gray.
The one most people think of is the natural graying that occurs as we grow older.
As we age our melanocytes become inactive, but are still present.
The older we get, melanocytes decrease in number.
The result is less and less melanin, until none are present.
Thus, we slowly turn gray, and then our hair turns white in the winter of our lives.
In February of 2005, Harvard scientists proposed a theory as to why melanocytes decrease as
we age.
They found that a failure of melanocyte stem cells was the cause.
These stem cells stop producing adequate numbers of melanocytes to maintain our color.
In 2009, scientists in Europe found another contributing factor.
They found that hair follicles produce small amounts of hydrogen peroxide.
As any teenager preparing for a concert knows, if you expose your hair to hydrogen peroxide,
it will make your hair lighter.
Normally this small amount of hydrogen peroxide is broken down by an enzyme called catalase.
As we age, catalase production is reduced.
The result is a build up of hydrogen peroxide, which blocks melanin production by melanocytes.
There are several other things that can cause our hair to turn gray.
The exact mediating factor of them isn't fully known.
Some include: genetic defects; abnormal hormone production like in the case of sudden or chronic
stress; abnormal body distribution of melanin; and climate factors can also cause graying,
such as pollutants, toxins, and chemical exposure.
As for stress, in 2011, the 2012 Nobel Prize winner in Chemistry, Robert Lefkowitz, led
a research group that discovered the mechanism that could explain why stress causes graying.
Stress causes a release of numerous neurotransmitters involved in our fight or flight response.
Normally the release of these neurotransmitters is short lived and has very beneficial attributes-
the ability to run from a chasing lion, or avoid an oncoming car to name a couple.
Long term production of these neurotransmitters, however, can cause DNA damage.
This damage was shown by this group to promote aging, the growth of tumors, miscarriages,
psychiatric conditions, and graying of hair.
The time and speed at which you will gray varies greatly.
It's determined by many, if not all, of the factors we’ve discussed here, such as your
genetic predisposition, chemical exposures, and the levels of chronic stress throughout
your life to name a few.
Bonus Fact: • The average scalp has 100-150 thousand
hairs.
Hair is so strong that if you made all of your hair into a rope, it could hold 10-15
tons or about 3.5 ounces per strand.
Hair also has the highest rate of cell division in the body.
It grows at .3mm per day on average, and 1 cm per month.
Thankfully, each hair has its own life cycle.
If it didn't, instead of losing hair randomly, we would molt.
On that note, hair grows in three phases: Anagen- The active growth stage (80-85% of
hair is in this phase); Catagen- This phase is also known as the transitional phase, when
hair begins to stop growing; and telogen- this phase is when hair growth is completely
shut down and the fibers fall out (10-15% of our hair is in this phase at any given
time).
After your hair goes through the Telogen phase, Anagen begins again and voila!
More hair!...
For some people… (BACK TO SINGLE TEAR SHOT FROM BEFORE)
As you might have guessed from this, hair length is completely controlled by the length
of the anagen phase of your hair follicle.
How long this period lasts is generally determined mostly by genetics, but can also be affected
by hormones, and even extreme stress, which in some cases can cause the majority of hair
on your body to rapidly transition to the telogen phase and fall out.
As to how, there is some chemical signal that ultimately controls the exact growth cycle.
However, it isn't yet fully known what exactly triggers the catagen phase beyond that, but
once it is triggered, the outer part of the root ends up being cut off from its nutrient
supply (blood), as well as the cells that produce new hair, thus your hair stops growing.
This phase lasts about three weeks.
As mentioned, next up comes the telogen phase where the follicle is in a resting state and
your hair is now a "club hair", completely dead down to the root.
During this stage, these hairs are relatively easy to pull out (as can happen while brushing/combing/washing
your hair), but if they manage to last long enough, they'll eventually be pushed out by
a new hair as the cycle begins again.
Obviously hairs on your arms or legs have a very different anagen period than hairs
on your head, thus why your leg hair doesn't grow two feet long without trimming.
Further, different people, thanks mostly to their genetics, have differing lengths of
the anagen period for a given body part compared to other people.
For the hair on your head, the average length of the anagen phase is about 2-7 years.
For your arms, legs, eyebrows, etc., this phase usually lasts just 30-45 days.
However, in extreme cases which are quite rare, some people have anagen periods for
their heads as small as most people's anagen phases for their arms and legs.
For these people, their hair never naturally grows more than a few inches long.
The opposite is also true, with people whose anagen phase can last decades for their scalp
hair.
Under normal circumstances, though, you can get a rough estimate of how long your anagen
phase is based on how long your hair grows naturally without cutting on a given area.
First, assuming your hair isn't already as long as it can get, measure your hair length,
then exactly a month later measure it again and note the difference.
Now you have your growth rate (usually about 1 cm every 28 days or 1 inch every 71 days).
So if, without cutting, the hair on your head eventually grows 16 inches long max, then
your anagen phase lasts: (inches*period per inch).
So using the average of 1 inch every 71 days, (16 inches * 71 days/inch) = approximately
1136 days or 3.11 years.
As you might have now guessed from the fact that hair growth is completely controlled
by what's going on under the surface, within your hair follicles, and that genetics and
hormones are the primary things determining hair growth length, which are in no way affected
by shaving, contrary to popular belief, shaving does not in any way alter your hair growth
rate nor does it alter the color
of the hair.