by Giulia Basevi & Dr Kiran Sodha - All posts, Hair Loss - 05/11/201814/05/2019 Hair Growth Did you know an average adult has around 100,000 to 150,000 hairs on their head, and it’s perfectly normal to lose up to a 100 per day! So when you see some on your hair brush, you probably don’t need to worry… What is hair made of? Each hair strand begins its life cycle as protein cells known as keratin in a hair bulb. These form the base of the hair follicle, found in the dermal layer of the skin. The hair follicle regulates hair growth, which is dependent on signals sent by hormones in the body, immune cells and neuropeptides. These substances allow the production of different types of hair present on different areas of the body. Hair growth stages There are different stages of hair growth, which helps to understand the different types of hair loss that we’ll come to. Hair growth is separated into 4 different stages of a cycle: Anagen This is the active growth phase where the cells in the root of the hair divide at a rapid rate. This phase of growth normally lasts for anything between two and seven years, which is why some people can grow their hair longer than others; the longer the anagen phase lasts for, the longer the hair will grow. The length that this occurs for varies mainly due to genetics between different people. Catagen The catagen phase is a short transitional stage that occurs at the end of the active growth (anagen) stage of the hair. This lasts between 2-3 weeks whilst the hair converts into club hair. During this process, the hair is cut off from its blood supply and becomes disengaged from the cells that produce new hair. Telogen This is the final stage before the hair falls out, also known as the resting phase and lasts for approximately 3 months. The club hair is now dead and fully keratinized. Exogen The final stage in the hair cycle where the club hair shafts are pushed out by the new hair in Anagen phase. So there you have it, hair growth on a page! For further information on hair loss and treatments available with The Doctor Service.