To prevent frizz, breakage, and other hair and scalp problems, don’t sleep on this advice: Don’t sleep on wet hair.
That’s the recommendation from hairstylist Sophia Royal, a Pure Brazilian educator and owner of Salon Philosophie in Vacaville, CA.
Air-drying over lengthy periods of time can actually cause more damage to the hair than blow-drying, she says. “Hair is most fragile when wet, and the cuticle remains open.
“When hair is wet, the hydrogen bonds are broken temporarily. Leaving the hair damp for hours on end — especially sleeping on wet or damp hair — damages the cuticle layer and over-exposes the cortex.”
In addition, moisture causes the hair's outer layer and inner cortex to swell. Repeated cycles of swelling and reduction cause damage called hygral fatigue, Royal says.
“Constant and excessive swelling and de-swelling of the hair causes strands to become weak, dry, and less elastic — leading to breakage, frizz, static, tangling, and even mildew.”
Hair that stays wet or damp for long periods can create ideal conditions for the growth of bacteria and fungi, she says.
“Educate your clients that drying their hair with a diffuser, blow dryer, or sitting under a hooded dryer is better than air drying,” Royal advises. “It’s a simple solution to some of their biggest problems."