CLAIM:

Sleeping with wet hair does not cause a cold because colds are caused by viruses, not by wet hair. However, going to bed with wet hair may leave the scalp damp for hours, which could contribute to discomfort, hair breakage or worsen certain scalp conditions in some people.

FACT:

Available scientific evidence does not support the claim that sleeping with wet hair causes the common cold. Colds are caused by respiratory viruses and spread through contact with infected people or contaminated surfaces – not by wet hair. However, sleeping with wet hair may leave the scalp damp for prolonged periods, increasing the risk of hair breakage and potentially aggravating existing scalp conditions in some individuals.

Remember being told, “Don’t go to sleep with wet hair, you’ll catch a cold”? It’s one of those pieces of advice many of us grew up hearing. Even today, after a long day, you may finish all your chores, take a relaxing shower and feel ready to fall asleep – only to pause because your hair is still wet and the old warning comes to mind. The belief remains so common that many people still wonder whether sleeping with wet hair can actually make them sick.

The claim has also gained traction on social media, with several videos circulating online. In a YouTube Shorts video posted by the MedExplicare page as part of its “30 Days, 30 Health Myths Decoding Challenge”, pharmacist Umar addresses this popular belief. Introducing the topic, he says, “Can sleeping with wet hair make you sick?” before referring to the familiar warning: “You have probably heard this before. ‘Don’t go to bed with wet hair, you’ll catch cold.'”

He then explains that although the claim sounds believable, it is not supported by science. “Sleeping with wet hair doesn’t cause colds. Colds are caused by viruses, not by wet hair,” he says. However, he adds that going to bed with wet hair may leave the scalp damp for hours, which can cause discomfort, increase hair breakage or worsen certain scalp conditions in some people. Concluding the video, he says, “Myth decoded. Wet hair won’t make you sick. But drying your hair before going to bed can be better for your hair and scalp.”

The video has reignited a question that many people have heard since childhood. But does sleeping with wet hair really increase the risk of catching a cold, or is it simply another long-standing myth?

What research says?

Available evidence does not support the claim that sleeping with wet hair can cause the common cold. While going to bed with wet hair may have some drawbacks, such as increasing the risk of hair breakage or leaving the scalp damp for prolonged periods, there is no scientific evidence that wet hair itself can make a person catch a cold.

Research consistently shows that colds are caused by viruses, and a person develops a cold only after coming into contact with a cold-causing virus. There is no research demonstrating a direct link between having wet hair and developing the common cold.

A 2012 paper proposed that exposure to cold with wet hair may contribute to sinus headache or pain behind the eyes, but not because it causes an infection. The authors hypothesised that cooling of the scalp could activate the body’s selective brain cooling mechanism, leading to temporary changes in the paranasal sinuses and blood flow that might trigger these symptoms. However, the paper presents a theoretical hypothesis, not clinical evidence, and does not conclude that wet hair causes the common cold or sinusitis.

Healthline similarly notes that the common cold has “nothing to do with being cold” but is caused by infection with one of more than 200 respiratory viruses, most commonly rhinoviruses. These viruses spread through “your nose, mouth, or eyes and is spread through droplets in the air when an infected person sneezes, coughs, or speaks. You can also catch it by touching a contaminated surface or hand-to-hand contact with an infected person.”

The 2019 C.S. Mott Children’s Hospital National Poll found that many parents and caregivers continue to rely on traditional beliefs to prevent colds, including avoiding going outside with wet hair. However, these practices are based on folklore, and there is no evidence that they reduce the risk of developing a cold.

A 2016 study did find that consecutive decreases in temperature and humidity were associated with an increased risk of rhinovirus infections. However, the researchers examined changes in weather conditions, not whether people had wet hair. Therefore, the findings do not support the claim that sleeping with or going outside with wet hair increases the risk of catching a cold.

Why is it still better to dry your hair before bed? 

Although sleeping with wet hair does not cause the common cold, research suggests that it may not be the best habit for hair and scalp health. Wet hair is more fragile than dry hair, and prolonged dampness may contribute to discomfort or aggravate certain scalp conditions in some people.

One reason is that wet hair is more prone to stretching and breakage. Hair can safely stretch by about 30 per cent of its original length when wet, but stretching beyond this may cause irreversible damage to the hair shaft. Tossing and turning during sleep can increase friction between wet hair and the pillow, making it more susceptible to tangling and breakage.

Sleeping with wet hair may also make a person feel colder, especially in cooler environments. A 2015 study found that the head loses more heat at lower temperatures, with significantly greater heat loss at 10°C than at 15°C or 20°C. While this does not cause a cold, it may make sleeping less comfortable.

Prolonged scalp dampness may also affect people who are prone to certain scalp conditions. A 2021 study identified species of the yeast Malassezia in hair follicles. This naturally occurring fungus is associated with conditions such as seborrhoeic dermatitis, and a persistently damp scalp may provide a more favourable environment for its growth in susceptible individuals. 

Similarly, a 2019 study suggested that dandruff may worsen during winter because of cold and damp conditions and changes in the balance of bacteria and fungi on the scalp. While wet hair has not been shown to cause dandruff, leaving the scalp damp for long periods may aggravate symptoms in some people.

Research also indicates that hair loss is influenced primarily by genetic and hormonal factors. A 2017 study noted that environmental factors and excessive grooming can also contribute to hair damage. Because wet hair is mechanically weaker, sleeping with it may increase hair breakage due to friction, although it does not directly cause hair loss.

Prolonged moisture may also contribute to clogged hair follicles and skin irritation in people who are already prone to acne or scalp disorders. 

Do experts agree?

Dr Shireen Furtado, Senior Consultant in Medical and Cosmetic Dermatology at Aster CMI Hospital, Bengaluru, said there is no scientific evidence that sleeping with wet hair causes the common cold.

“Colds are caused by viruses, not by sleeping with wet hair or exposure to cold temperatures,” she said. According to Dr Furtado, viruses such as rhinoviruses spread through respiratory droplets and contaminated surfaces. “Wet hair itself cannot create or carry these viruses in a way that causes infection,” she added.

She explained that while some people may feel colder or uncomfortable after going to bed with wet hair, this should not be mistaken for catching a cold. “Good hand hygiene, avoiding contact with infected people, adequate sleep and a healthy lifestyle remain the best ways to reduce the risk of the common cold,” she said.

Dr Furtado added that although wet hair does not cause illness, it can affect hair and scalp health. “Hair is more fragile when wet, so friction against a pillow may increase breakage, tangling and frizz,” she said. She also noted that keeping the scalp damp for long periods may worsen existing conditions such as dandruff or seborrhoeic dermatitis in susceptible individuals, although sleeping with wet hair does not directly cause fungal infections.

She advised allowing hair to dry naturally before bed or using a hair dryer on a cool or low-heat setting, along with maintaining good scalp hygiene.

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