While there are some very rare hair shaft conditions such as Netherton’s Syndrome (aka bamboo hair) where the individual is born with hair that breaks very easily, effecting children before the age of three.
Also Pili Torti (discovered by Schutz in 1900) where the hair is fragile and the hair is reported to be “un-combable” by parents of effected children. the vast majority of breakage and hair weakness is caused externally, known mechanical damage.
Fragitalis Crinium, caused by a hair band worn too tight
A hair shaft that is broken is officially known as Fragitalis Cranium, this could be at the distal end (aka split end) or along the actual hair shaft length. This is where the outer cuticle of the hair is damaged to a degree and threatens the integrity of the cortex section of the hair, therefore the overall quality of the shaft. This is most common in hair that has been over-processed, too much heat, straightening irons, aggressive styling (ie bristle brushes), infrequent trimming of the hair and lack of general care and conditioning.
One particular reason I see in clinic to answer “why” is when irons and heated tongs are used when the hair is too wet. This can create Bubble Hair, it is described as being a localized defect within the hair itself. The cortex develops areas that resemble blisters within the structure which most often result in hair breaking at any point of the hair- which presents in patients with “chewed looking hairs” of varying length which are incredibly porous and dry feeling. This is a classic result of heat applied regularly over 180 degrees.
In the last five years patients have increasingly reported confusion as to why their hair feels dry and unmanageable when they use conditioners and “pre heat sprays to protect”. While styling heat and sunlight have always had a negative effect on the condition of hairs, It is my belief that some of these heat protectors with a high oil content are partially to blame for a lot of the damaged hair I see these days. If you are using heat so very hot to the touch, perhaps the styling technique needs to be reviewed.
If your hair feels suddenly very tangled and will not behave in the way it used to, feels rough to the touch and looks frizzy or fly away in nature it is likely your hair has been externally damaged in some way. It is a self-perpetuating scenario since the more your blow dry and pull the hair around a brush, the more damage it causes and the more you will need to style to calm down the frizzy look of this damaged hair.
Aside from reducing heat and extending the time between colours and highlights, protection is important too to lessen the chance of weather damage. Wearing a hat will help, spf cream or spray will protect like a sun tan cream does the skin between the hottest times of the day between June –September.
I suggest using a daily, in-shower conditioner helps to detangle and rehydrate. Along with a weekly deep conditioning mask to treat the hair and prevent more breakage. Some advocate a silk pillowcase to reduce static at night and hair band choices should be considered such a invisible bobble style- worn a differing locations of the scalp to reduce repetitive traction or wear and tear on the hair shaft.
This is an interesting question since many consultations I carry out pose this dilemma, it is not always obvious is the strands of hair “coming out” are broken hairs, out of condition or full length good condition hairs signifying an actual shedding condition. This is where an experienced Trichologist comes in to help decipher, through styling questions, diet and a thorough examination a condition such as Telogen Effluvium compared to weaker and porous hair would be clear to see and a solution could then be discussed.