Bringing this back from the dead because: http://www.npr.org/templates/story/s...69&ft=1&f=1001
It's a daily ritual for many (4.59 times a week on average), but NPR asks you to consider why, exactly, you're shampooing your hair every single day. It's not always necessary, and can actually harm your hair. Photo by flash.pro. National Public Radio's story, available in text and audio, details the history of the social ideal of washing one's hair every day, and talks to some stylists and dermatologist who say the oil your scalp produces to protect your hair, or sebum, is stripped away and forced to produce at a higher level—kind of like the chest-shaving paradox explored in Seinfeld.
"If you wash your hair every day, you're removing the sebum," explains Michelle Hanjani, a dermatologist at Columbia University. "Then the oil glands compensate by producing more oil," she says.