Should A Humidifier Run All Night?

This article answers the question: ‘Should A Humidifier Run All Night?’

Humidifiers can help relieve symptoms of coughing, dry skin, and itchy throat. But many people also use humidifiers to combat snoring, and help them sleep better at night. 

And while using a humidifier is completely safe and healthy, it might not be a good idea to leave it running all night long. 

In fact, there are a couple different risks associated with leaving a humidifier running all night. 

Generally, you can use a humidifier at night while you sleep. That said, it is possible that your humidifier works a bit too well, and increases the humidity level to uncomfortable levels.

This in turn can cause problems such as breathlessness, allergic reactions, and the like. 

We research and test all things ‘humidifier’. So if you were having trouble figuring something out, you came to the right place. Allow us to answer all of your humidifier-related questions. 

Keep reading for more information about running humidifiers all night long.

So Should A Humidifier Run All Night?

Well, the answer isn’t as cut and dried as that. If you ask us, a humidifier shouldn’t necessarily run all night long. In fact, it depends on how you use the humidifier and what features the humidifier offers. 

To put it in so many words, it is perfectly safe to run a humidifier at night while you sleep. However, there are some important considerations and conditions that need to be met before we can sign off on running it all night long. 

In that vein, it is important to understand how humidity and humidifiers work, the effects of very high moisture content in the air, and what might be causing it. 

Humidity and Comfort 

Humidifiers increase the relative humidity of a given space, plain and simple. The reason you might want to increase the humidity of your bedroom, living room, office, or baby nursery is to combat the effects of low humidity. 

Those include coughing, allergic reactions, sinus problems, dry/cracked skin and lips, excessive snoring, and even trouble sleeping. Suffice to say, low humidity can cause a lot of discomfort. 

In fact, most people agree that they are at their most comfortable between 30%-50% relative humidity. To put that into perspective, the relative humidity of indoor spaces can drop to below 10% in winter months!

So the only real concern with running humidifiers all night is that they increase the humidity too much, which can have some adverse effects on you and your home. 

Effects Of High Humidity

Increased Temperature

Excess moisture in the air brings up the temperature of your surroundings. Sure, that’s great for when it’s freezing out, but while you sleep at night, it can be a bit uncomfortable. 

Most people prefer the ambient temperature of their bedroom to be a bit lower while sleeping. High humidity brings the temperature up, which could affect the quality of your sleep, especially if you’re used to sleeping in colder conditions. 

Increased Sweating

The higher temperature could also cause you to sweat more. At the very least, you’ll end up with sweaty sheets. However, excess sweating could result in your body losing too much water and becoming dehydrated. 

Allergic Reactions

You might have heard that humidifiers help lessen allergic reactions. That is absolutely true, but if you increase the humidity too much, it can have the opposite effect. A high amount of water vapor in the air could make it a breeding ground for bacteria, allergens, and other microbes that cause allergic reactions. 


Mold can also develop in very damp and humid conditions. This is especially true if you haven’t been keeping up with the maintenance of your humidifier. That includes regular cleaning and replacing the filter. 

A humidifier that isn’t properly maintained can develop mold in the water tank. This mold can very easily be released into the atmosphere, where it can cause a variety of diseases, allergies, and other health problems. 

Respiratory Problems

Very high moisture content in the air could make it harder for you to breathe. Think of trying to jog in the summer months after it just rained. 

You may experience breathlessness, and if you suffer from asthma, you may notice an uptick in symptoms. Moreover, very high humidity can actually cause chronic coughing to get worse. You may even experience a tightness in your chest. 

It’s not just your health that is affected by very high humidity. If you leave the humidifier running all night long, your house suffers too. 

Peeling Paint/Wallpaper

High moisture content in the air can cause paint and wallpaper to start peeling or develop air pockets that ruin the finish. Actually, this brings up another health concern. Peeling paint can release paint particles into the air, which can cause a host of respiratory/sinus problems, from rashes and allergies, to breathlessness and asthma. It is even possible that the toxic paint particles cause you to develop other, more serious conditions. 

Wood Panels Become Dislodged

High humidity can cause wood to expand and deform. You’ll have noticed this with doors that just don’t seal properly in humid weather. The same applies to wood floors, paneling, and the like. 

Most wooden furniture also doesn’t react well to very high humidity. Furniture can become deformed, lose its sheen, and even crack or break in very high humidity. 

Why Is The Humidity So High?

Say you turn on your humidifier, set the humidity to around 40%, and go to sleep. How and why would it go any higher than that? Well, there are a couple different reasons your humidifier is increasing the humidity too much. 

Sensor Malfunction

Modern humidifiers regulate humidity, which means they only increase humidity up to a preset level. Most come with an auto mode that uses integrated sensors to figure out the relative humidity of your space. However, like any component, these sensors can become faulty. 

If so, they might not register the relative humidity accurately, causing the humidifier to increase it even further. 

Your Humidifier Has Been Running At High Settings

Alternatively, you might just be using the humidifier by manually adjusting the mist volume, speed, and other settings. If so, you might have set the humidity level, the mist speed or volume too high. This can cause the humidity to keep getting higher and higher, which can become a problem. 

How To Prevent Uncomfortably High Humidity While You Sleep

So what can you do to prevent the humidity from becoming too high and causing problems? Well there’s a couple things to keep in mind. 

Use The Timer Function

If your humidifier comes with a timer function, we highly recommend using it. Configuring the humidifier to turn off after a while might be a good idea if you sleep with it on. 

Lower The Mist Speed 

Higher mist speeds humidify a space much faster than slower speeds. But if you leave the mist speed set to high while you sleep, it could cause over-humidification. Lower the mist speed if you run your humidifier while sleeping for a more comfortable experience. 

Lower The Mist Volume

Mist volume is the amount of water vapor being released into the air per hour. Higher mist volumes mean faster humidification. It is also great for humidifying larger spaces. But again, this feature can easily cause too much moisture in the air. Lowering mist volume should prevent the excess humidity you might be feeling at night. 


So then, should a humidifier run all night? Well, despite everything we’ve just talked about, we still think that running a humidifier all night is safe. That said, there are some important conditions!

First and foremost, you must ensure that the auto mode on your humidifier works as it should. If not, or if you just want to be on the safe side, you should take over manual control of the humidifier settings. 

Here, the idea is that since the humidifier is running all night, even lower mist/volume settings will be quite effective at humidifying your space. 

Lastly, if you want to use the high humidity settings while you sleep, we highly recommend setting the timer to turn the humidifier off after a while. In fact, some modern humidifiers come with a feature that lets you schedule times for the unit to turn on or off at predetermined times. 

If you don’t implement these safeguards, running a humidifier could be disastrous to both yours and your house’s health.


Shawn Willis is all about humidifiers. After working for some of the biggest names in the industry, he started HumidifierGuys with Scott Dawson. Now, the dynamic duo helps others figure out what they need in their next humidifier.

Shawn is an avid sports fan, motorcycle enthusiast, and has two dogs named Whiskey and Boba.