How Does Indoor Air Quality Impact Sleep?

Sleep is essential for mental health, physical health and your overall quality of life. Chronic sleep deficiency can affect brain function and heart health, as well as increase the risk of certain health conditions, such as diabetes, obesity, kidney disease and stroke.

Unfortunately, sleep is often one of the first things to be sacrificed when schedules fill up. Moreover, even if you manage to get a full night of shuteye, indoor and outdoor air pollution can decrease the quality and the health benefits of your sleep.

A 2017 study found that people who lived in areas with high levels of outdoor air pollution were 60% more likely to sleep poorly than those in regions with less pollution. Another study found poor ventilation can also lead to restless nights and groggy mornings.

Here, we break down the different ways that poor air quality may affect your sleep and what you can do to decrease your nighttime exposure to air pollution.

How can pollutants impact sleep quality?

You may find it easier to fall asleep when your bedroom is cool and there is a slight breeze from a fan or open window. Stuffy, warm rooms can make it feel almost impossible to fall, and stay asleep because of the difference in comfortable temperature as well as air quality between the two scenarios.

Ventilation is one of the most significant determining factors of a room’s air quality. If you sleep with your windows and doors shut, carbon dioxide levels in your room can rise to 2,500 to 3,000 parts per million (ppm) while you sleep. This is about three times the recommended levels.

Overnight exposure to elevated levels of carbon dioxide can lead to lower sleep efficiency (the amount of time you spend asleep in bed compared to the time you spend awake). This 2016 study found that decreased sleep caused by a lack of ventilation may lead to decreased cognitive function the following day.

Do mold and other allergens affect how well you sleep?

Carbon dioxide is not the only indoor air pollutant that can accumulate in the air overnight if a room is not well-ventilated. Mold and other allergens can also affect sleep by causing allergy symptoms, especially nasal congestion, to flare up while you are in bed. 

Many allergy triggers, such as mold, pet dander and dust mites, are often found in the bedroom and in bedding. When you are constantly exposed to these triggers for an entire night, you may find yourself experiencing nighttime nasal congestion that leads to insomnia, restless sleep and daytime sleepiness.

The most common sleep-disrupting allergens found in the bedroom are mold, dust mites, pollen, pet dander and cockroaches. The presence of some allergens, such as pollen and mold, may depend on the season. However, many allergens can be found in the bedroom year-round.

Can particle pollution disrupt sleep?

In a study presented at the American Thoracic Society’s annual conference in 2017, researchers revealed that exposure to a specific type of particle pollution called PM2.5 was linked to an increased chance of low sleep efficiency. The study’s authors found that people living in areas with higher exposure to PM2.5 were more likely to have disrupted or restless sleep than people with low levels of exposure.

PM2.5 is a category of particulate matter made up of tiny particles or droplets in the air with a width of 2.5 microns or less. These particles are considered more dangerous than larger particles because they are small enough to travel deep into the respiratory tract when inhaled. Some may reach your lungs and even enter your bloodstream.

Exposure to PM2.5 has been linked to short-term symptoms that include coughing, sneezing, runny nose and shortness of breath, as well as eye, nose and throat irritation. Longer-term effects may include decreased lung function, worsened asthma symptoms and increased mortality risk from lung cancer and heart disease.

Symptoms of PM2.5 exposure can cause breathing issues that lead to disrupted sleep, according to the study’s authors. However, it is possible that sleeplessness may also be a direct effect of pollution exposure. 

How is air pollution linked to sleep apnea?

Sleep apnea is a disorder that causes your breathing to stop and start again repeatedly while you sleep. It can disrupt sleep and lead to daytime fatigue, drowsiness and irritability. Sleep apnea is also linked to a range of potentially serious complications, including:

  • Increased risk of type 2 diabetes: Sleep apnea may increase your chance of developing insulin resistance and type 2 diabetes.
  • Elevated blood pressure: If you have sleep apnea, you experience multiple sudden drops in your blood oxygen levels throughout the night. This can increase your blood pressure and strain your cardiovascular system, leading to hypertension (high blood pressure).
  • Metabolic syndrome: Sleep apnea may increase your risk of metabolic syndrome, a disorder associated with high blood sugar and blood pressure, abnormal cholesterol levels, increased waist circumference and increased risk of heart disease.
  • Liver problems: Individuals with sleep apnea may experience an increased risk of abnormal results on liver function tests and nonalcoholic fatty liver disease.
  • Increased risk of heart problems: Some types of sleep apnea may increase your risk of heart complications, such as heart attack, stroke and abnormal heartbeats. In people with heart disease, nightly episodes of low blood oxygen are associated with mortality caused by irregular heartbeats.

A recent study found a link between exposure to air pollution and risk of developing sleep apnea. Researchers noted that, among the study participants, odds of having sleep apnea increased significantly with increased exposure to PM 2.5 and nitrogen dioxide. 

The study was not a randomized, controlled trial, so the authors cannot prove that air pollution causes sleep apnea. However, they do note that improving indoor air quality may directly contribute to better sleep health.

What can you do to increase indoor air quality while you sleep?

When trying to improve the air quality in your bedroom, one of the most important considerations should be ventilation. While a cool breeze may make it easier to fall asleep, it will not improve air quality unless it comes from a source that is cleaner than your indoor air. Turning on a fan and opening a window or door can help keep carbon dioxide from building up to dangerous levels, but it may not help with other types of pollution. 

If the air outside your home is more polluted than the indoor air, opening a window could actually increase your indoor air pollution. Depending on the source of your indoor air pollution, opening an interior door may be a better method of ventilation.

A portable air purifier can also increase the airflow in your bedroom, replacing polluted air with clean air. Sleeping with an air purifier on can help decrease nighttime air pollution exposure that may affect your quality of sleep. To get the most benefit from your bedroom air purifier, try placing it close to your bed at about the same level as your head (such as on a nightstand). Make sure the air intake is not blocked by a wall or other obstruction. It cannot replace adequate ventilation, however, which prevents carbon dioxide build-up.

Removing mold and other allergens at the source

Though ventilation and air purification can help manage levels of airborne allergens in the home, source control will make the biggest impact. For mold, this means getting rid of any sources of standing water — leaky pipes, gaps in window frames, unventilated bathrooms and kitchens. 

If you find mold in your home, use diluted bleach to clean the area and kill the mold growth. As long as the mold growth covers less than 10 square feet (and the mold is not a recurring problem in that area), you should be able to clean it on your own without needing to contact a specialist.

Dust mites are another common pollutant found in bedrooms. Though it is impossible to rid your room of dust mites completely, you can help decrease their presence in your home by reducing the humidity, using dust mite-proof bedding and removing places they like to gather, such as carpets, curtains and upholstered furniture.

Other ways to reduce the presence of allergens in your bedroom include:

  • Washing your bedding weekly in warm water;
  • Keeping pets — and, therefore, pet dander — out of your bedroom;
  • Showering before you go to bed to reduce the amount of pollen and other allergens you bring into the bedroom;
  • Dusting regularly with a microfiber or damp cloth that traps allergens instead of kicking them up into the air;
  • Removing unnecessary dust-gathering clutter from your room;
  • Keeping your windows closed on days when pollen, mold or other outdoor pollution levels are high.

A note about sleep apnea

If you or someone in your household has sleep apnea, air cleaners and source control may not be enough to help improve sleep quality. This resource from the American Sleep Apnea Association lists different options that you can discuss with your medical provider to determine the best way to treat your specific situation.

Often, the bedroom is the most-used room in any home. Because you spend so many hours in there each night, the air quality in your room can have a big impact on your quality of sleep (and your overall health). Improving the air quality in your bedroom is an essential step in caring for your sleep health so you can wake up each morning feeling rested and refreshed.