Professor Nicola Ralph Featured in the Irish Independent on Sleeping With Wet Hair
Professor Nicola Ralph, Consultant Dermatologist and Co-Founder of the Institute of Dermatologists, contributed her expertise to the Irish Independent's Stay Well column this week, in a piece by Features Writer Filomena Kaguako tackling one of the most persistent myths in hair care: that sleeping with wet hair will make you sick.
Sleeping with wet hair won't give you a cold, colds are caused by viruses, not damp hair, but it isn't entirely harmless either. According to Professor Nicola Ralph, a damp scalp can create the perfect warm, humid environment for yeast to overgrow, which may lead to dandruff or seborrhoeic dermatitis in some people, while the hair itself is more prone to breakage when wet.
Does Wet Hair Actually Cause Colds?
No. "Colds are usually caused by viruses, not by having wet hair, so that's definitely a myth," GP Dr Ahmeda Ali, medical director at Webdoctor.ie, told the Irish Independent. "It's not going to make you seriously ill."
Can a Damp Scalp Really Cause Dandruff?
It can, in some people. "It may encourage the microorganisms to grow as they have the perfect warm, damp environment to thrive in," explained Professor Ralph. "This may result in Malassezia [yeast] overgrowth resulting in seborrhoeic dermatitis."
"For some susceptible individuals the damp environment may lead to increased presence of yeast which could result in dandruff, but this does not always occur." — Professor Nicola Ralph
Is Wet Hair the Main Cause of Seborrhoeic Dermatitis?
Not usually. "Air-drying the hair or having a damp scalp is only one reason why someone may develop seborrhoeic dermatitis, and is certainly not something I see commonly in clinical practice," Professor Ralph said. Far more often, she explained, it comes down to an overreaction to Malassezia, genetics, oily skin or scalp, stress, or certain neurological conditions, and sometimes simply not washing the hair enough or leaving too many products on the scalp between washes.
What Does This Mean for Your Hair Care Routine?
The practical takeaway isn't to avoid wet hair altogether, it's how it's managed. A gentle, scalp-friendly shampoo such as CLn Shampoo can help support a scalp that's already prone to irritation, and Professor Ralph's advice on regular washing and avoiding product build-up applies whether hair is dried naturally or with heat.
Are There Any Upsides to Air-Drying?
For some hair types, yes. "There are no real medical downsides to letting hair dry naturally in someone who has fine, thin hair, as it avoids using heat which can damage the hair leading to breakage over time," said Professor Ralph. Trichologist Ioan Mares, also interviewed for the piece, added that hair is at its weakest when wet, so friction from a pillow, brushing, or tying it up while damp can increase breakage.
Frequently Asked Questions
Will sleeping with wet hair give me a cold?
No. Colds are caused by viruses, not by having wet or damp hair, a myth with no medical basis.
Can sleeping with wet hair cause dandruff?
It can in some people, since a damp scalp creates conditions where yeast can overgrow, though this doesn't happen to everyone.
Is a damp scalp the main cause of seborrhoeic dermatitis?
No. Genetics, an overreaction to naturally occurring yeast, oily skin, stress, and infrequent washing are all more common causes than damp hair alone.
Is it fine to occasionally sleep with wet hair?
Yes, occasional wet hair is unlikely to cause problems for most healthy people. It's a regular habit that's best avoided.
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Thank you to Filomena Kaguako and the Irish Independent for featuring Professor Nicola Ralph and the Institute of Dermatologists.
