Mandy’s Musing…Hey Brains!! Great website!! I’m a sucker for healthy hair and methods on keeping it healthy, and I was surfing through the net and found this article: http://www.tlhs.org/vid06.jpg. What do you think? Is it possible for hair to get used to not being washed and therefore not producing so much oil so that it won’t look greasy over time? Could this method keep hair at it’s healthiest? Wouldn’t this cause dandruff?
The Left Brain’s Learned Reply:
Interesting question, Mandy. Let’s start with the last part of your question first: Does not washing your hair cause dandruff? No, it doesn’t. Dandruff is caused by a combination of over active sebaceous glands and bacteria. If you don’t have dandruff, skipping your shampoo won’t “give” it to you.
Oil control
Now, let’s talk about how oil (also known as sebum) gets on your scalp in the first place. Sebum is generated in tiny sebaceous glands beneath the surface of the skin. These glands produce an oily substance that reaches the skin’s surface through hair follicles. Some sebum is a good thing – it’s a natural moisturizer and it keeps your skin and hair soft and supple. But, some people are prone to excess sebum production and that can be too much of a good thing. (If you’re interested, you can find some excellent background information on sebum at dermnet.)
When you ask if your hair can get used to not being washed you’re implying that leaving oil on your hair will somehow stop the production of more oil. The flip side of that implication is that stripping away the oil with a shampoo will make your glands produce more oil. Well guess what. That’s exactly what DOES happen. Sort of.
Gland-tastic
To understand how this works, you have understand how sebum production is regulated – in other words what turns the sebum glands on and off. It turns out that it’s the presence of sebum on the surface of skin that controls sebum production. How is that possible? Well, if you REALLY want to know, go read this study in which scientists stripped oil off skin and then measured how long it took the skin to re-oil itself. Their data indicates that the presence of oil on the skin’s surface sends a signal to the sebaceous glands to turn off. This signal is caused by either the pressure of the oil in the follicle or by the creation of a chemical signal that travels back down through the skin. So it turns out that, in theory, you can “train” your hair to be less oily.
Shampoo and sebum
But then why doesn’t shampooing make your scalp oilier and oilier? That’s because the oil production levels off very quickly. Here’s how that works:
If you wash your hair you remove all the sebum on your scalp and that triggers your sebaceous glands to produce more oil. But once they’ve produced enough sebum to cover the your scalp, all that oil sends a signal to shut off production. So, you only end up with a certain amount of oil on your scalp – let’s call that amount “x.”
Now lets say that you don’t wash your hair – the sebum will still build up until it reaches “x ” amount. But then, the glands get the message to stop producing more oil. So, unless you take some of the sebum away, you still end up with “x” amount on your scalp. See how that works? Even though washing away sebum does trigger more sebum to be produced the sebum production levels off once the oils hits the scalp. The notion that washing your hair triggers more oil, which then makes you wash your hair again, which in turn gives you MORE oil so you end up with 2x or 3x oil on your hair or skin is just not true.
Of course, this is the case for healthy skin. If you have over-active sebaceous glands you can end up with oil skin or hair. But it’s not the shampooing that’s causing the excessive oiliness.
The Beauty Brains bottom line
Depending on your hair type and how oily your skin is naturally, you might benefit by not washing your hair as much. That would be an interesting experiment to conduct. But don’t skip shampooing just because someone told you that it makes your hair oilier. That’s just not true.