Most people know that a cool, dark, quiet sleep environment is best for sleep, but inappropriate humidity can also negatively impact sleep. Dry winter air can lead to a baby or toddler waking due to a persistent cough, itching, or thirst. Introducing a humidifier may help eliminate these night wakings and help your child sleep soundly. However, recent studies have raise concerns about the quality of air produced by a humidifier. As a result, it’s important to incorporate a cleaning routine when you introduce a humidifier to your child’s sleep environment.
The Science: The optimal humidity for the sleep environment is between 40-60%. When humidity is low, the ambient temperature feels colder than it actually is and when humidity is high, the ambient temperature feels hotter. This means that in the winter, when humidity is generally low, a cool room can feel cold. Since ambient temperature and humidity are so closely linked, you need to make sure that you adjust the thermostat in your child’s room if you aren’t able to adjust the humidity very much. For example, if you normally set your thermostat to 68 degrees in the summer, when humidity is around 50%, then you may need to increase the ambient temperature by a few degrees in the winter when humidity levels are low.
Low humidity levels can affect more than just how cold a room feels. When humidity levels are low, children are more prone to nosebleeds, itching, and dry eyes. Dry environments can also exacerbate cold symptoms and cause coughs to linger after other symptoms have subsided. For children with eczema, both low and high humidity can cause flare ups. Introducing a humidifier to your child’s room may help to keep her comfortable, by helping to hold warmth in the room and by reducing discomfort.
Although humidity is helpful for the sleep environment, there have been a few case reports in the medical literature over the last 10 years showing that improper use can lead to poor outcomes. Several studies have shown that humidifiers can spread bacteria and microorganisms if they aren’t cleaned properly and often. Conversely, some of the cleaning products that people use to eliminate bacteria contain volatile chemicals that can create dangerous aerosols and particles. When these contaminants are inspired daily, they can cause serious negative health consequences. As a result, it’s important to keep your humidifier clean without the use of such chemicals.
If you think a humidifier will help your child sleep, then there are a few things to consider when selecting and using one:
Ease of Cleaning is Important! When choosing a humidifier, select one that is easy to clean and make changing the water part of your daily routine. It’s important to clean the humidifier at least once every three days. You may find it easiest to incorporate changing the water into your child's bedtime routine, so that you don't forget.
Warm Mist or Cool Mist? There isn’t a lot of data on which of these two options is better. Whichever you choose, research suggests that cleaning is the most important consideration.
Check Your Water. Some of the negative effects associated with humidifier use appear to come from contaminants in water interacting with the air. Tap water is likely safe if you keep your humidifier clean. If you want to exercise extra caution, then consider using distilled water. Distilled water won’t eliminate all hazards, but it will minimize the likelihood of the water itself causing a problem.
Do not use Humidifier Disinfectants. So-called “humidifier disinfectants” that are designed to be diluted into the water reservoir and left in the humidifier while it is running have been associated with serious respiratory disease and lung injury in both children and adults.
Avoid Humidifiers with Bright Lights. For some reason most humidifiers have bright lights on them and in many cases those lights are blue! If you follow our blogs, then you know that our bodies consider blue light to be alerting, so it’s best to choose one that doesn’t light up.
Only use Humidifiers when Necessary. If your child has a lingering cough or a bout of itchy skin, then you may want to introduce a humidifier into her room to help her sleep. When the seasons change and there is more moisture in the air, you don’t need to keep using a humidifier.
If you aren’t sure whether it makes sense to introduce a humidifier to your child’s sleep space, then talk to your pediatrician for further guidance.
One of the Baby Sleep Science team members was the senior author on a publication describing the environmental parameters necessary for an optimal sleep environment (Caddick et al. 2018). In our “Sleep Environment” series we’ll be going through all of the studies that have been conducted on each element of the sleep environment to help you create the best sleep environment for your child.
Tyndall RL, Lehman ES, Bowman EK, Milton DK, Barbaree JM. Home humidifiers as a potential source of exposure to microbial pathogens, endotoxins, and allergens. Indoor Air. 1995 Sep;5(3):171-8.
Mohan AK, Feigley CE, Macera CA. Humidifier use in the home environment and its effects on respiratory health. Applied occupational and environmental hygiene. 1998 Nov 1;13(11):782-7.
Daftary AS, Deterding RR. Inhalational lung injury associated with humidifier “white dust”. Pediatrics. 2011 Feb 1;127(2):e509-12.
Yang HJ, Kim HJ, Yu J, Lee E, Jung YH, Kim HY, Seo JH, Kwon GY, Park JH, Gwack J, Youn SK. Inhalation toxicity of humidifier disinfectants as a risk factor of children’s interstitial lung disease in Korea: a case-control study. PLoS One. 2013 Jun 5;8(6):e64430.
Sain AE, Dietrich AM. Emission of inhalable dissolved drinking water constituents by ultrasonic humidifiers. Environmental Engineering Science. 2015 Dec 1;32(12):1027-35.
Park JH, Kim HJ, Kwon GY, Gwack J, Park YJ, Youn SK, Kwon JW, Yang BG, Lee MS, Jung M, Lee H. Humidifier disinfectants are a cause of lung injury among adults in South Korea: a community-based case-control study. PLoS One. 2016 Mar 18;11(3):e0151849.
Caddick ZA, Gregory K, Arsintescu L, Flynn-Evans EE. A review of the environmental parameters necessary for an optimal sleep environment. Building and environment. 2018 Mar 15;132:11-20.