Does air quality affect sleep? Yes, here’s how.

The quality of the air in your bedroom affects your sleep. It affects how quickly you fall asleep, the quality of your sleep, and your performance the next day. Humidity levels and temperature influence how easily you fall asleep, and air pollutants increase your chances of sleep disorder.

Poor sleep can have a significant effect on how you feel. It affects your mood, overall wellbeing, and clarity of mind. the quality of sleep also affects your performance the next day, and how well-rested you feel.

Let’s have a look at the effects of poor air quality on sleep, and what you can do about it.

Air quality affects sleep in many different ways. It can affect:

  • Your quality of sleep
  • The time it takes to fall asleep
  • The feeling of sleepiness the next day
  • Your ability to concentrate the next day
  • Symptoms of dryness of nose, throat, and skin

The most important air quality factors and their effects on sleep

There are many different aspects of air quality such as air pollutant levels, humidity, and temperature. They all affect your sleep in a different way and there are different measures you can take to control them.

The most important aspects of air quality for sleep are:

  • CO2 levels in your air
  • Humidity level of your room
  • Room temperature
  • The presence of airflow
  • Air pollutants

In this article, we take a look at each of these air quality factors individually and see what you can do about them.

What causes poor indoor air quality?

Poor air quality has many causes including cooking, off-gassing materials, and pollutants coming from the outdoor air. You can read all about the causes of air pollution in my article: This is what causes your poor indoor air quality.

The effect of elevated CO2 levels on sleep

Elevated levels of CO2 can be harmful to our health. For negative effects to occur, levels of CO2 need to be higher than 1000 ppm (parts per million). From these levels onward, complaints of poor air and drowsiness start to occur. These levels of CO2 are actually quite common, especially in poorly ventilated bedrooms, because of CO2 build-up during the night (due to your breathing).

Studies on CO2 levels and sleep show that sleep quality and the perceived freshness of bedroom air improved significantly when CO2 levels were lower. Additionally, next-day sleepiness, the ability to concentrate, as well as performance on a logical thinking test, were significantly better when the level of CO2 was below 1000 ppm during sleep.

If you want to read more about CO2, you can read my article: What are healthy indoor CO2 levels? (safe levels, health effects and what to do about them)

How to reduce CO2 levels

The best and easiest way to reduce CO2 levels in your bedroom is to ventilate. You should be ventilating your bedroom and the rest of your house constantly for the best air quality, and for CO2 it’s is no different. Most rooms have some ventilation grilles and vents that you can open. Otherwise, opening your window does the trick.

Try to keep the ventilation open the whole night. Otherwise, CO2 levels can build up. You can install mosquito nets to prevent insects from entering your bedroom.

For even better ventilation, open several doors inside the house to allow for airflow between open windows and ventilation vents.

The effect of humidity on sleep

One important aspect of sleep quality is the time it takes for you to fall asleep. Falling asleep requires, among others, the ability for your body to lose some heat. This is more easily achieved with relatively low air humidity.

The optimal level of (relative) humidity is between 30 and 60 %. Within this range, you will have no symptoms related to dry or humid air unless you are especially susceptible to air humidity.

Humidity levels vary with air temperature. Warm air can hold more moisture than cold air. Therefore, the air is generally dryer in winter. This happens especially when ventilation, and therefore fresh air, is minimized to prevent heat loss during the winter.

Interestingly, humidity has less effect on a feeling of dryness than air pollutants. So if you have complaints about dry skin, eyes, throat, etc. You will likely have more succes focussing on cleaner air rather than on optimal humidity.

How to adjust humidity levels

Humidity levels can be lowered by about 5 to 10 percent by opening your window. If you have severe humidity issues in your house, you should consider buying a humidifier or dehumidifier. They are surprisingly affordable. You can check their pricing here on amazon.

The effect of room temperature on sleep

As mentioned above, temperature and humidity are strongly related. Optimal room temperature results in less time required to fall asleep as well as better sleep quality.

The optimal temperature when humidity is at a comfortable level is between 17 and 28 degrees Celcius (63 to 82 degrees Fahrenheit). Men are more comfortable at lower temperatures while women prefer higher temperatures.

  • Men: 17 °C (63 °F) and higher
  • Women: 23 °C (73 °F) and higher

This temperature range assumes you are able to choose your bedding and can adjust the bedsheet covering of your body during the night.

How to adjust the temperature of the room

Depending on the outdoor temperature, opening or closing the window changes the temperature slightly. But likely not more than a total of 2 degrees Celcius difference (4 °F). Of course, the temperature change depends on the difference between the indoor and outdoor temperature.

Other options to regulate the temperature are installing fans or an air conditioning system. Better insulation as well as insulative curtains, and other ways of blocking sunlight such as blinds or shutters can help with temperature control.

The effect of airflow on sleep

Not many studies have been done on the effect of airflow on sleep quality. The ones that have, mention that there seems to be no effect of airflow on sleep outcomes. However, the people participating in one of these studies mentioned that they prefer to sleep with airflow. On top of that, they preferred a constant airflow of 0.6 meters per second over intermittent airflow.

How to provide airflow

You can provide airflow in your bedroom in several ways. The most simple way is to sleep with an open window. More than one open window allows for easier airflow as the air can move between the two windows. Another option is to open doors inside the house to allow for airflow between rooms.

Additionally, a fan or an air purifier can provide some airflow. Air purifiers, however, are not designed to increase airflow. So if you want airflow from your air purifier you need to buy one with a high ACH (air changes per hour). You can read all about air changes per hour in my article: How long should you run your air purifier?

The effect of air pollutants on sleep

Air pollutants can affect your health in many different ways. One study analyzed the medical records of almost 400.000 elderly for a period of 10 years. They looked at the levels of air pollution as well as their hospital visits related to sleep disorder.

This study concluded that traffic-related air pollutants (fine dust and NO2) were the main offenders in causing sleep disorder. Additionally, this study showed that women might be slightly more susceptible to air pollution in relation to sleep disorder compared to men.

How to reduce air pollutants

Since indoor air is often 2 to 5 times worse than outdoor air, the most effective way to reduce air pollutants is normally to increase ventilation. In the case of traffic-related air pollution, this is still the case since outdoor air pollutants entering your room can get trapped inside when the air is hardly moving. Allowing airflow between outdoor and indoor air at least lowers your indoor pollution levels to the outdoor concentration.

Nightly ventilation is especially important because traffic reduces during the night and the air becomes cleaner. Another good habit is to air out your house around 2 o’clock during the day. This is the time of day when outdoor air pollution from traffic is at its lowest (even compared to the night). This is due to a decrease in traffic compared to rush hours and because warm air moves more compared to cold nightly air.

When the outdoor air is heavily polluted I recommend looking for alternatives to ventilation. An air purifier is a great tool for This, as it can remove fine dust and gases. If you want to know more about air purifiers, please read my article: How to know if you need an air purifier (+ what it does and doesn’t do).

Summary: air quality for optimal sleep

To achieve the best sleep possible, make sure your bedroom air has:

  • (relative) humidity between 30 and 60 %

Sleeping with an open window can lower humidity by 5 to 10 %. A humidifier or dehumidifier can help overcome more severe humidity issues.

  • A temperature between 17 and 28 degrees

Men prefer 17 degrees while women prefer 23 degrees. Make sure you are able to play around with your bedsheet covering during the night for optimal sleep. Additionally, sleeping with an open window can help control temperature a little (max 2 °C/ 4 °F difference). A fan or air conditioner can help overcome more severe temperature issues.

  • CO2 levels below 1000 ppm

Sleeping with an open window helps with ventilation and reduces CO2 levels. Good ventilation will be sufficient to prevent CO2 levels from becoming too high.

  • Some airflow

Although not scientifically proven to improve sleep quality, participants in sleep and air quality studies mentioned that they have a preference for continuous airflow. Preferably 0.6 meters per second.

To conclude, the best sleep is mostly achieved by opening bedroom windows during the night. Other options are installing a fan or purchasing an air purifier or (de)humidifier.

I hope you are able to improve your sleep and feel and perform better.

Using an air quality monitor to improve sleep

To make sure you are always aware of the levels of CO2, VOCs, and other harmful substances in your house, an air quality monitor is an excellent tool. An air quality monitor can measure airborne chemicals, temperature, and humidity, depending on the device.

If you are interested in buying an air quality monitor, I would recommend choosing a model that measures a wide range of air pollutants. In this way, you never have to worry if you are missing just that one compound that is causing problems.

A Norwegian company called Airthings produces some of the best-rated air quality monitors on the market. They can detect many air pollutants and are easy to operate (just wave your hand in front of the device) and send their data to an app on your phone.

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