Hey Doctor R,
I was just wondering about growth cycles of hair. In terms of non-scalp hair, or body hair, which tends to have a shorter growth phase – what happens here? Like do the genes which navigate hair growth just shut off after the hair reaches a particular length? Like I began to get curious about this when I trimmed some body hair – but did not shave it completely off. After, it is trimmed the hair begins to grow again and stops at the same length.How does the hair “know” its been cut? Do the genes controlling hair growth become active again when body hair is trimmed or shaved? I know this is kind of a weird question, but I thought you may be able to provide me with some kind of explanation. Thank you!’
Body hair grows to a certain length and also has a different growth / rest cycle than scalp hair. Scalp hair has a longer growth cycle, which is why you can have your scalp hair grow very long. When it is cut short, the impact of gravity is lessened, and its character is more evident. People with crew cuts have a bristly feel of the scalp, but when the hair is very long, its weight impacts they way it looks. The characteristics of the hair is genetic.
Hair is not sentimental, does not feel pain and holds no grudge when it is cut short.