Should A Humidifier Run All Night – Benefits And Risks


A humidifier can be run all night if the relative humidity level is below 50%. Ensure the humidifier has an auto shut-off feature, has surge protection and is at least 3 feet away from the bed. Only use distilled water and ensure the filter is clean. A humidifier can improve the quality of sleep by reducing the effects of dry air, inflammation in the airways and snoring.

Nose bleeding, cracked lips, and sinuses are some of the common problems in dry weather. To prevent these issues, many people use humidifiers during the nighttime, especially in Winter. 

If you use a humidifier in the bedroom and are considering leaving it running all night, safety should be your primary concern. This article will detail the benefits and downsides of running a humidifier all night, and highlight some safety measures.  

  • A humidifier can be kept on all night when the indoor relative humidity level is below 50%.
  • Operating a humidifier at nighttime can reduce the risk of contracting viruses, help retain skin moisture and improve sleep quality by reducing snoring and inflammation in the airways.
  • For the best results, select a quiet humidifier without a heating element, and place it at least 3 feet away from where you sleep.

Humidifiers and sleep

Humidifiers are used to increase the moisture level in the air. They do this by releasing water vapor, which results in an increase in humidity. By adding moisture to the air, a humidifier can be a great device for several health conditions, including skin dryness, asthma, snoring and flu. 

In fact, during the height of the COVID-19 pandemic, 4 billion USD worth of humidifiers were sold in 2020. This high demand was due to rising respiratory symptoms and conditions, including asthma and sinus inflammation, especially during winter. 

The optimal humidity level for both comfort (including while sleeping) and health is between 30% to 50%. If you regularly experience a sore throat, dry skin, cracked lips, or even a bleeding nose (especially during winter) your surroundings may have a humidity level that is less than 30%.

A humidifier can increase the humidity in your home and help combat the symptoms of dry air.

Humidifiers can be particularly helpful if you suffer from snoring.

Humidifiers reduce inflammation along our airways, and can help relieve nasal congestion and throat irritation. Several studies have now shown that increasing humidity levels can help reduce snoring – giving us a better nights sleep.

Plentiful Air has comprehensive information on how humidifiers can help reduce snoring available here.

However, excessive use of humidifiers can also open the getaway to several issues. It can even worsen existing respiratory problems if used incorrectly, so it’s imperative to know how to use them efficiently. 

Types of Humidifiers  

There are different types of humidifiers, many of them have the same benefits and risks when it comes to operating them through the night. However, some (especially those with heating elements) come with more risks than others.

In general, there are four types of humidifiers:  

  • Central Humidifier  
  • Evaporators  
  • Ultrasonic Humidifier  
  • Impeller Humidifier 

Central Humidifier  

Central humidifiers are built directly into the HVAC system of your house. A central humidifier is expensive but can effectively maintain the humidity levels in large areas, such as living rooms and basements.  

These units are particularly useful in larger homes, or family homes. Rather than having a separate humidifier for each room, or bedroom, a central humidifier can replace the cost of several units, and is also easier to operate and maintain.

Evaporators  

Evaporators consist of a moistened filter that blows out moisture. They are affordable and can only be used in one room at a time. 

Ultrasonic Humidifiers 

The most expensive and high-quality types of humidifiers. Ultrasonic humidifiers produce a soothing and mist through ultrasonic vibration. Ultrasonic humidifiers come in varying sizes and capacities, including cool and hot mist versions. 

Impeller Humidifiers 

Impeller humidifiers are also called cool mist humidifiers. They release a cool mist of water vapor. The impeller humidifier contains a spinning disk that releases moisture into the air. These humidifiers are louder than other types as they have an electric motor.  

Benefits And Risks Of Leaving A Humidifier on All Night

Keeping a humidifier on all night depends on the existing humidity level of the indoor air.

If the humidity level of your space is less than 30%, leaving a humidifier all night is (in general) a good option.  

However, it is important to monitor the humidity level.

If the humidity reaches above 50%, it is best not to have a humidifier on all night.

According to Energy Star, a humidity level above 50% can be perfect for bacteria and fungi growth. Higher humidity levels can also lead to condensation, another way of inviting hundreds of harmful microorganisms to your home.  

Almost all humidifiers contain sensors that monitor humidity levels.

As a result, most humidifiers automatically shut down if the humidity level goes above average. On most units you can also select a maximum humidity level, ensuring your humidifier will turn off and not continue to disperse water vapor unnecessarily.

Benefits of Keeping a Humidifier on All Night

A humidifier is helpful both in summer and winter. Although, most people use a humidifier during the wintertime as the air is naturally dried out.  

On the other hand, some people experience respiratory issues, including hayfever and flu, during the summer. It’s because the hot temperature creates an ideal condition for bacteria and pests. As a result, the air contains more bacteria and allergens.  

During summers, fans and air conditioners circulate the dry air through our homes, further eliminating the moisture from the air.

So, while we often associate using a humidifier with winter, using a humidifier on summer nights can also be a great idea.

Dry and cold air in the wintertime also removes the moisture from your skin, leading to various irritations, including dryness and itchiness. A humidifier can also help prevent these problems during winters. 

Running a humidifier all night is highly beneficial, whether it’s hot summer or long cold winter nights.   

Here are some specific benefits of running a humidifier all night: 

1. Effect on Influenza and Other Viruses  

According to a medical study, running a humidifier all night can reduce the risk of catching viruses, including influenza. Researchers found that higher humidity levels can reduce the effect of virus particles and bacteria.

This makes viruses in the air less infectious. 

So if you keep the humidifier on all night, you can worry less about potential viruses in your environment.  

2. Better Sleep Quality  

Low and high humidity levels impact the air quality.  

A low humidity level can lead to irritation and dryness of the skin and throat. The dryness in the air can result in mucus production, making it difficult to breathe and disrupts your sleep.

Running a humidifier all night can maintain an optimal moisture level in the air, leading to a reduction in dry air irritations and snoring, and a better and more comfortable sleep.  

3. Maintains Skin Moisture 

Skin is an important part of the human body. It is the first line of defense and barrier against microbes such as viruses and bacteria, from entering. 

Prolonged exposure to dry air can cause itchiness and cracks in your skin. As a result, it gets easier for viruses and bacteria to impact your overall health.  

Leaving the humidifier on all night can help leave your skin moisturized, preventing viruses from entering your body. A sufficient amount of moisture can make your skin softer, hydrated, and more elastic.  

As per medical studies, moisturized skin can lessen the risk of contracting various viruses and developing many chronic diseases, including diabetes, cardiac problems, and Alzheimer’s. 

Possible Risks of Keeping A Humidifier on All Night  

Improving the humidity of the indoor air can be great, but possible risks of keeping a humidifier on all night may include:  

1. Water Tank Running Dry  

It’s easy to measure the water levels during the day. However, you won’t be able to monitor the water levels while sleeping.

To prevent this issue, choose a humidifier whose timeline for mist production is longer than your sleep hours. A humidifier with an auto shut-off sensor is also a great choice as it can turn off automatically if the water tank runs dry. 

2. Higher Electricity Bill 

According to the EPA, humidifiers are responsible for an average of 0.11% of electricity consumption in every US household. So, using a humidifier all night can impact your electricity bill. Also, keep in mind that the type of humidifier you buy also influences electricity consumption.  

For example, the average cool-mist humidifier uses 130% more energy than an ultrasonic one. Although, an ultrasonic humidifier can be energy-efficient and are estimated to save around 11.8 kWh a year (compared to the average humidifier). 

3. Increased Asthma and Allergy  

A humidifier can produce white dust (scale) along with the mist. The white dust is the mineral residue from the tap water used in the humidifier reservoir.

Keeping the humidifier on every night can result in not only scale deposit, but also regular dirt and dust residue. As a result, you can be exposed to numerous allergens and infections.

To mitigate this risk, clean the humidifier every night before turning it on, and always rinse the reservoir when refilling it.

4. Fire Hazard 

A humidifier is an electronic device, and like any other appliance, running a humidifier all night can overheat it.

Overheating appliances are a fire risk. Ensure that your humidifier has an auto-shut off feature, and ideally have it plugged in with surge protection to help minimize the risk.

5. Annoying Noise  

Every humidifier produces noise. Although, ultrasonic humidifiers are the quietest.  

According to the CDC, the standard humidifier emits fewer than 30 decibels, which is the sound level of a soft whisper. However, they still produce a humming sound (gurgling sound, humming, water droplets sound) that can be annoying and interrupt your sleep.

Plentiful Air has a complete guide to the quietest humidifiers available here.

How to Reduce the Risks of Keeping a Humidifier on All Night

If you want to run a humidifier all night, here are some tips to prevent the above-mentioned risks from happening: 

  • Use a Hygrometer to monitor humidity levels 
  • Don’t use tap water in the humidifier (only use distilled water)
  • Clean the filters regularly
  • Change the water every night 

Common Concerns of Running A Humidifier All Night

Leaving a humidifier on all night isn’t always entirely safe.

You will have to consider several factors before doing so, including:  

1. How Many Hours Should You Run a Humidifier?  

There is no rule of thumb to determine the proper usage of a humidifier. However, the best time limit to use a humidifier constantly is around 10-12 hours a day.  

Remember that running a humidifier more than this can lead to a significant increase in moisture level of your room. Therefore, running a humidifier all night is safe only if you keep tabs on the humidity level and your overall usage.  

2. When Is the Best Time to Switch off Your Humidifier?  

If you run your humidifier all night then you can switch off your humidifier in the morning. Relative humidity levels are at their highest first thing in the morning (this is why we see dew on the grass in the morning).

The naturally higher humidity levels are the perfect time to turn your humidifier off – this prevents it from overheating and gives you a chance to clean and refill it, especially if you are likely to be using it again the next night.

The best time to switch off your humidifier is when humidity levels are above 50%. Remember, according to the Environmental Protection Agency, indoor relative humidity should not exceed 50% as it can lead to excessive condensation, and offer ideal conditions for bacteria to thrive.

And of course, always remember to turn your humidifier off if you leave the house!

3. What is the Best Time to Use a Humidifier? 

The best time to use the humidifier is in the winter. The moisture and steam provided by the humidifier can ease common symptoms brought about by the cold temperature and drier air.  

Low temperatures in winters can result in physical and health discomfort, including itchy throat, dry nose, chapped lips and cracked skin. However, humidifiers can help you tackle all these concerns.  

In terms of a daily cycle, the best time to use a humidifier is at nighttime. This is when humidity is typically at its lowest, and you are more likely to experience the symptoms of dry air.

Other than using a humidifier in winter and/or at nighttime, using a humidifier when the relative humidity in your home drops below 30% is ideal.

4. Can You Leave a Humidifier on 24/7?  

It is safe to leave a humidifier on 24/7 if it has an auto shut-off feature and is plugged in with surge protection. Only use distilled water and ensure the filter is clean. These steps can help minimize any risks of overheating or fire.

Ideally, turn your humidifier off after 10-12 hours and allow it to rest for 30 minutes. Taking necessary precautions and maintenance steps can eliminate the downsides of the frequent running of a humidifier. 

FAQ 

Is It Okay To Sleep Next To a Humidifier at Night? 

A humidifier should be placed at least 3 feet away from where you sleep. If running a humidifier at night, select a humidifier that does not have a heating element, such as a cool-mist ultrasonic unit.

Should a Humidifier Run All Night for Plants? 

A humidifier should not be run all night for plants. During the night, plants do not photosynthesise and do not absorb any moisture. A humidifier can be used to provide moisture to plants during the day. Increased humidity can boost plant growth, allowing them to retain optimal moisture

The best time to provide plants with humidity through humidifiers is during sunrise and midday. You can run the humidifier for around 4 to 5 hours.

Plentiful Air has detailed information on how and when to use humidifiers for plants available here.

Should You Sleep With a Humidifier During Winter? 

A humidifier is quite helpful to sleep with, especially during the winter. The common reason to use a humidifier during winter is to relieve and prevent the health concerns associated with dry and cold air.  

Sleeping with a humidifier during winter can increase the moisture level in your bedroom. As a result, the air can feel warm and make it easier to breathe. So, it is great to use a humidifier during winter.  

Theresa Orr

Theresa Orr is an Earth Scientist who specializes in determining past climates from rocks using geochemistry. Her passion for clean water, soil and air drives her to provide easy to understand information for everyone to read.

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