# Sebum

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Sebum is the reason your second-day hair often looks better than your freshly washed hair. It's a mix of triglycerides, wax esters, squalene, and cholesterol produced by sebaceous glands at the base of each hair follicle — chemically, it's the closest natural product your body makes to a conditioning oil.

On straight hair, sebum travels easily from root to tip, lubricating the whole strand. On [curly, coily, or coarse hair](/hair-types/), the twists and turns stop the journey — roots get oily while ends stay dry. This is why curly hair benefits disproportionately from conditioners that re-deposit lipids the scalp couldn't deliver on its own.

When you strip sebum aggressively (with [sulfates](/glossary/sulfate/), for instance), the scalp reads the deficit and ramps up production. Over a few weeks of gentler washing, production normalizes downward — which is why many people find they can wash less often after switching to a sulfate-free shampoo.