Is It Bad to Sleep With Wet Hair? What's Real and What's Myth

Plenty of us were marched back to the bathroom with a towel on the grounds that wet hair gives you a cold. It doesn't. The towel was still good advice, for a duller reason that involves hydrogen bonds.

Two things happen when a wet head meets a pillow: a strand that has temporarily changed how it behaves gets rubbed for hours, and a scalp stays damp for much of the night. The first is well understood. The second rests mostly on dermatologists' experience, and we'll say so when we get there.

Is it bad to sleep with wet hair?

Once in a while, not very. As a habit, it can be. Shilpi Khetarpal, MD, a Cleveland Clinic dermatologist, says hair is more fragile when wet and can break as it rubs against the pillowcase, and that doing this often can cause harm over time. A late shower before a 6 a.m. flight isn't going to ruin anything. Five nights a week for years is the version worth changing, especially if your hair is bleached, permed or already snapping.

Why is wet hair weaker than dry hair?

Water loosens the bonds that keep hair stiff. Hair is mostly keratin, a protein, and water disrupts the hydrogen bonds and salt bridges that hold its chains in place, so the strand stretches under much less force.

You'll often read that wet hair snaps at half the force of dry hair. We couldn't trace that figure to a study, and the measurements we did find tell a different story. In a 2022 study in the International Journal of Cosmetic Science, untreated hair tested in water broke at about 17% less stress than hair tested in ordinary room air, while its stiffness was roughly halved. So healthy wet hair still takes real force to break, but it gives far more under the same tug, and every turn of your head on the pillow is a tug. Bleached hair has less in reserve: in the same study it lost noticeably more strength than natural hair when wet, and very little when dry. A separate lab comparison found the same pattern for permed hair.

The internet has a name for the other worry: hygral fatigue, the idea that swelling and shrinking wears hair out. The evidence is thin, since much of the lab work mixes water with heat and tension. One result does give pause. In a 2011 test in Annals of Dermatology, swatches washed and left to air-dry for over two hours, 30 times running, showed damage in the fatty layers between the hair's cells. Swatches dried with a hair dryer didn't. The authors could only speculate that long contact with water was the cause, and a lab swatch isn't your head. It's still a reason not to keep hair wet for eight hours when ten minutes would do.

Can you catch a cold from sleeping with wet hair?

No. Colds are viral: more than 200 respiratory viruses can cause them, rhinoviruses most often, and they travel in droplets from coughs and sneezes and on hands and surfaces. A family medicine doctor at the University of Arkansas for Medical Sciences says there is "no medical evidence" that going to bed with wet hair gives you one. You may wake up chilly. You can't conjure a rhinovirus out of a damp pillow.

Can sleeping with wet hair cause scalp problems?

It may for some people, though the evidence is mostly clinical experience. Dr. Khetarpal says moisture on the scalp encourages bacteria and yeast, which can lead to dandruff and to folliculitis, the acne-like bumps that form around hair follicles. We didn't find a study that followed people who regularly sleep with wet hair, so nobody can give you your odds. If you have flaking, itching, bumps or sore spots that don't settle, see a board-certified dermatologist. Several scalp conditions look alike and need different care, and this article can't tell them apart.

How dry should your hair be before bed?

Aim for a dry scalp and lengths that feel slightly cool and damp, rather than wet. No study sets a number, so treat that as sensible practice.

• Shower earlier if you can. An hour or two makes a real difference on fine hair and less on thick hair.
• Blot, don't rub. The American Academy of Dermatology warns that rubbing hair dry can cause damage. A towel or an old T-shirt, pressed gently, does the job.
• Dry the roots on low. Dr. Khetarpal suggests a low or cool setting if you need speed. The AAD prefers air-drying when you can, while the 2011 study favored a moving dryer about 6 inches (15 cm) away over hours of air-drying. Nobody defends the other extreme: in that study, the hottest, closest setting did the worst surface damage.
• Comb with care. Use a wide-tooth comb. The AAD says to let straight hair dry a bit first and to comb textured hair or tight curls while damp.
• Keep it loose. A soft, low braid or loose twists will do, with no tight elastic.

If your hair is thick or tightly curled and takes most of an evening to dry, work toward the dry scalp and keep the lengths sectioned. Setting damp hair in loose twists or braids is a long-standing part of many textured-hair routines, and it's a different thing from lying on a soaking head. The full nightly routine is in how to protect your hair while you sleep, and if your complaint is mostly morning fuzz, why hair frizzes overnight picks it up from there.

Does a silk pillowcase make it OK to sleep with wet hair?

A silk pillowcase softens the friction and does nothing about the wetness. Dr. Khetarpal suggests satin or silk for that first reason, and many people find a smooth surface means fewer tangles in the morning. The strand underneath is still swollen and stretchy, though, your scalp is still damp, and the pillowcase will get damp too. You've made one part of the problem smaller. A bonnet has the same limit and one more, since a covering slows drying, so put it on once your hair is nearly dry.

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You can stop blaming wet hair for your colds. Whoever handed you that towel was still onto something.

Frequently asked questions

Is it OK to sleep with damp hair?

Slightly damp lengths are a long way from soaking wet, and most people do this without trouble. Try to get your scalp dry and keep the hair in a loose style. If your hair is bleached or breaks easily, it's worth drying it further.

Can sleeping with wet hair cause hair loss?

We found no good evidence that it affects hair at the follicle. It can add to breakage along the strand, and a lot of broken hair can look like thinning. If you're shedding more than usual or see patches or a receding hairline, see a board-certified dermatologist, because hair loss has many causes.

Does sleeping with wet hair cause dandruff?

It may contribute for some people. A Cleveland Clinic dermatologist says moisture on the scalp encourages yeast and bacteria, which can lead to dandruff, but we didn't find a study measuring the risk. If flakes or bumps persist, a dermatologist can tell you what they are.

Is it better to blow-dry your hair or go to bed with it wet?

For most people, a few minutes on a low or cool setting is the better choice. High heat close to the hair does the most surface damage, so keep the dryer moving and several inches away. Stop when your hair is nearly dry.

Should you braid wet hair before bed?

A soft braid can keep long hair from tangling, but don't pull it tight. Wet hair stretches easily, and a tight braid strains both the strand and your hairline. A thick braid may also still be damp by morning, so get as much water out as you can first.

How long does hair take to air-dry?

It depends on length, thickness and the room. In one lab test, a small swatch of hair took over two hours to dry at about 68°F (20°C). A full head of thick hair can take much longer, sometimes most of the night.

Related reading: Why Your Hair Tangles While You Sleep · Silk Bonnet vs Silk Pillowcase: Which Should You Buy First? · The Silk Pillowcase Guide