Hair speaks volumes. The way we cut, style and colour often acts as a representation of who we are.

But hair is more than just aesthetic. It also has many important functions – preventing heat loss from the skin for instance, or (in the case of our eyebrows) stopping sweat dripping into the eyes.

Hair can be a reflection of what’s going on inside our body, too. Many diseases can alter the quality and appearance of our hair. Paying attention to the way it looks can give us clues to the state of our health.

Some of the tiniest organs in our bodies are the follicles which produce and nourish hairs. Hair can only grow where follicles exist.

Hair growth is a complex process. Each tiny follicle goes through different cyclical stages. The first is the stage of active hair growth (the “anogen” phase), before growth is arrested (the “catagen” phase). This then progresses to the stage when the hair is lost or shed from the follicle (the “telogen” phase).

Many factors – from our genetics to our hormones to our age – can affect these follicles and their growth.

Hypertrichosis is a condition where hair grows in excess all over the body. In most cases, this is a reaction to starting a new medication, such as phenytoin, which is used to treat epilepsy. But it may also be caused by diseases, such as anorexia and HIV.

Some........

© The Conversation