How can that be? First, a little hair anatomy: Each strand of your hair is essentially a tube with an inner cortex and a protective outer layer (called a cuticle) held together by delicate proteins. “When the cuticle layer is perfectly intact, then hair is very shiny and doesn’t tend to break,” says Jeff Donovan, MD, a board-certified dermatologist and hair restoration physician with Hair Club Medical Group in Toronto. Too much heat can damage the cuticle by trapping water inside the cortex and actually causing the water to boil (yikes). Sounds like a case for air-drying, but get this: The study found that while the heat of a dryer can cause more damage than not using one, using a hair-dryer at the right distance and temperature can actually cause less damage than letting hair air-dry. That’s because when hair comes in contact with water, it swells. The longer the swelling goes on (say, for the 2 hours it took for hair to air-dry in the study), the more pressure it puts on the delicate proteins keeping hair intact, which can lead to more damage. Here’s the just-right formula for drying your hair the healthiest way possible: First, let your hair dry naturally, about 70-80% of the way dry. Then, with your dryer on the coolest setting (don’t touch that hot setting!), blow your hair dry, keeping the dryer about 6-inches away from hair at all times and moving it around continuously. Voilà: gorgeous, healthy hair, without the heat. More from Prevention:
