Going outside or to bed with wet hair does not increase the risk of becoming sick. However, warm and damp environments, such as a pillow in contact with a person’s wet hair, may lead to infections on the scalp or face.

Hair performs the following roles:

  • mechanical protection for the skin from the external environment
  • increasing the sensory function of the skin
  • aiding regulation of body temperature

While wet hair may not directly make someone sick, water absorption causes the hair shaft swelling.

The moisture from the hair will also dampen the pillow. Going to bed with damp hair can increase the risk of developing a fungal or yeast infection on the scalp, as yeast finds it easier to grow in warm or moist areas of the body.

Read on for the effects of wet hair, the risks of sleeping with wet hair, precautions, and tips to avoid sleeping with wet hair.

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Myths passed from generation to generation may make people think that going to bed or outside with wet hair can make a person ill.

Below are two common questions regarding wet hair and the common cold.

Can wet hair cause a cold?

Research suggests that simply having wet hair does not make people unwell.

According to the Centers for Disease Control and Prevention (CDC), adults in the United States typically have 2–3 colds per year. Viruses cause colds, and the only way to develop a cold is to come into contact with a cold-causing virus.

There is no research to support a direct correlation between the common cold and having wet hair. Only exposure to a cold-causing virus can cause a person to develop a cold.

Can going out with wet hair in the cold cause a cold?

The 2019 Mott Poll report suggests that some parents and caregivers use folklore strategies for preventing the common cold.

However, spending more time indoors or outdoors or not going outside with wet hair has not been shown to actually make a difference in the risk of developing a cold.

However, a 2016 study found that decreases in temperature and humidity over consecutive days may increase people’s risk of rhinovirus infections — a cause of colds.

No research suggests that the risk of developing a cold correlates with having wet hair.

Read more about the common cold and cold weather.

There are reasons why people may wish to dry their hair before going to bed. Wet hair may cause the following:

  1. Hair stretching: Wet hair stretches by around 30% of its original length without damage. However, irreversible changes occur when hair stretches between 30–70%. Sleeping on the hair may cause it to stretch beyond tolerable lengths.
  2. Feeling cold: A study in 2015 showed that people’s heads lost more heat when exposed to cool temperatures. There was significantly greater heat loss at 10 degrees Celsius (°C) than at 15°C or 20°C. This means wet hair may lead to more uncomfortable sleep.
  3. Growth of fungus: Researchers in 2021 found a species of Malassezia fungus in hair follicles. This fungus can result in skin conditions such as seborrheic dermatitis. Hair being wet for long periods, such as overnight, may increase the risk of these conditions developing.
  4. Dandruff: A 2019 study suggested that the winter temperatures exacerbate dandruff due to the cold and wet conditions. The same study suggested that a balance of bacteria and fungi may also play a part in the condition. Wet hair may lead to heat loss, meaning it may worsen dandruff.
  5. Hair breakage: According to a 2017 study, genetic and hormonal changes are significant factors in hair loss. However, the environment and excessive grooming may also play a part, such as going outside with wet hair. Wet hair when sleeping also can cause damage to follicles and result in hair breakage.
  6. Skin conditions: Hair follicles under the skin clogged up with sebum or oil can result in acne. As wet hair harbors bacteria, this can also impact the growth of bacteria in the pores. Hair being wet for long periods, such as overnight, may increase the risk of these conditions developing.

People can take steps to avoid going to bed with wet hair. Doing so can help prevent issues associated with leaving hair wet.

The simplest step is to dry the hair as much as possible before going to bed.

People can also ensure that their bedroom temperature is comfortable. Experts recommend 60–67°F (15.6–19.4°C) as the optimal range.

Showering or bathing 1–2 hours before bed can also give hair a chance to dry naturally.

To avoid hair damage, the American Academy of Dermatology suggests that people:

  • condition their hair every time they wash it
  • gently comb wet hair with a wide-toothed comb
  • wrap their hair gently in a towel to absorb water rather than rubbing it with a towel
  • air dry hair where possible
  • avoid pulling hair back tightly with a band, as loose styles are better for hair

Read on for ways to repair damaged hair.

To reduce the chance of damage or issues from having wet hair when sleeping, a person can try the following techniques.

Wash hair less

The number of times people wash their hair in a week is down to preference.

A study from 2015 suggests that a person may wash their hair every day without causing an issue. Frequent and regular cleaning with a well-formulated shampoo will not damage the hair.

However, drying long hair with heat-based tools may result in damaged hair. If individuals can wash their hair every other day or go longer between washes, this may reduce the time they lie on a damp pillow.

Read on about daily hair washing and alternatives.

Lengthen the time between washing and sleeping

A person may wish to try starting their bedtime routine earlier, including washing their hair earlier. This could help them have drier hair by the time they go to bed. This can help reduce the risk of it being damp and creating an environment for fungus to grow.

Read on for ways to improve sleep routines.

Using conditioner

To keep hair healthy and reduce the risk of damage, people can use either conditioner or a two-in-one conditioner (also known as 2-in-1 shampoo) every time they wash their hair. After shampoo, the silicone ingredient in the conditioner replaces sebum oil, making the hair shiny, soft, and free of static electricity.

Protein-derived substances in conditioners can temporarily mend split ends.

A person may also use a leave-in conditioner as an additional step, as it may help improve hair health.

Argan oil or coconut oil

Some types of oil may be beneficial for hair as they penetrate the outer cells.

Research from 2015 shows that coconut oil can reduce protein loss in undamaged and damaged hair. Meanwhile, argan oil helps to moisturize hair.

These oils may suit particular types of hair, so people should take care applying them and consult a doctor or dermatologist if they have any concerns.

Learn more about the best essential oils for hair.

Sleeping and going out with wet hair cannot give a person a cold. However, doing so may have some disadvantages, including hair breakage and an increase in yeast and fungal overgrowth on the hair. People may decide that they should alter their routine to allow more time for drying their hair.

People may wish to avoid practices that could damage their hair, including using tight bands, heat-based styling products, and a comb with narrow teeth.

They may also want to find the best products available to look after their hair by speaking with a doctor or dermatologist.