When, where, and how your hair grows can seem like a huge mystery especially since there are so many factors that can affect it. As an example, we can look at one of our customers, let’s call her Cassie, who loooooooved her hair while pregnant. But once her bundle of joy arrived, her hair was not the same. It felt dryer than normal, she had a ton of new hairs frizzing around the crown of her head and her hair began to shed a lot! Cassie was freaking out. Raise your hand if you’ve been there!
Part of this is due to hormonal changes that can happen during pregnancy. Hormones can encourage and prevent hair growth, which can be frustrating when attempting to grow out hair. Here we are going to describe the basic hair growth stages: anagen, catagen, and telogen. To help customers like Cassie understand the growth phases and how it can effect hair density and length.
The first stage is the longest of the growth cycle and can last anywhere from a few months up to 8 years for a single hair! On average, the anagen phase will be at its longest length in your late teens to mid-twenties. The amount of time hair will spend in the anagen phase is coded into our genes and regulated by hormones known as androgens, which can either promote or prevent hair growth. And which are currently being researched for their precise effects.
In the first zone of the follicle, the cells in the root of the hair divide and replicate. (Think back to high school biology) Nutrients and hair pigment are added through the dermal papilla to the bulb and help fuel this activity. As the cells divide, they move up the follicle, moving into the keratinization zone.
This is when cystine links are formed in the keratinization zone, creating strong bonds that help form the tough keratin scales. This means that the keratin is beginning to stabilize into its cuticle structure, but is still too malleable to fully protect the hair. As they proceed to the third zone, they become dehydrated and the cuticle scales become a smooth and stable surface. This is caused by a mild oxidative process (gain of oxygen) that changes the cystine linkages to disulfide bonds, which in turn strengthens the hair cuticle.
The catagen stage is a very short phase (a few weeks to a few months) that begins the transition from growth (anagen) to resting (telogen). Cell division slows down in the follicle and the bulb begins to migrate to the surface.
Now the bulb has moved far enough away from the blood vessels that it can no longer receive nutrients. Growth is halted and the bulb has reduced in size, allowing a new root to start developing. This new root is beginning the anagen phase and helps to push the old hair completely out of the follicle.
This phase is where Cassie’s pregnancy hormones helped keep her hair thick and shiny! Hormonal shifts during her pregnancy would decrease the amount of androgens responsible for jumpstarting the telogen phase. Without the specific androgens, less hairs will begin reducing in size to make way for new growth. Once the hormones shift after pregnancy, not only will the telogen phase become more active, but it will affect the hairs that are past their prime and the hairs scheduled to shed. This sadly means adding hair catchers in the shower to catch all those shedding hairs. But remember, hairs falling out lead to new growth!
There are many factors that can affect hair growth cycles. One way you may be able to turn the tide in your favor is through regular scalp massage. This stimulates blood flow to the scalp and aids in hair growth. Here are two scalp massagers we like:
Alexander P. Fellows, M. T. (2020). Nanoscale Molecular Characterizaiton of Hair Cuticle Cells Using Integrated Atomic Forc Microscopy-Infrared Laser Spectroscopy. Applied Spectroscopy, 1540-1550.
Cibele Rosana Ribeiro de Castro Lima, R. A. (2019). Heat‐damaged evaluation of virgin hair. Journal of Cosmetic Dermatology, 1885-1892.
Duane P. Harland, R. J. (2014). Three-dimensional architecture of macrofibrils in the human scalp hair cortex. Journal of Structural Biology, 397-404.
Faduma M. Maddar, D. P. (2019). Nanoscale Surface Charge Visualization of Human Hair. Analytical Chemistry, 4632-4639.
Jordana Dias dos Santos, H. G. (2019). Raman Spectroscopy and electronic microscopy structural studies of Caucasian and Afro human hair. Heliyon , e01582.
Monika Grymowicz, E. R. (2020). Hormonal Effects on Hair Follicles. International Journal of Molecular Sciences, 5342.
Rita de Cassia Comis Wagner, P. K. (2007). Electron microscopic observations of human hair medulla. Journal of Microscopy, 54-63.
Sandra L. Koch, M. D. (2019). Variation in human hair ultrastructure among three biogeographic populations. Journal of Structural Biology, 60-66.
Xu Liwen, Liu Kevin X., and Senna Maryanne M. (2017) A Practical Approach to the Diagnosis and Management of Hair Loss in Children and Adolescents. Frontiers in Medicine. 4(112). doi: 10.3389/fmed.2017.00112