If Opening a Window Leads to Better Sleep, Why Don’t We Do It?

A flurry of recent studies find that sleeping with a window open Trusted Source Science Direct The leading platform of peer-reviewed literature that helps you move your research forward. View Source — or improving bedroom air with a ventilation system Trusted Source Science Direct The leading platform of peer-reviewed literature that helps you move your research forward. View Source when we can’t open a window — may help us sleep better. That isn’t lost on Craig Epstein.

The 23-year-old research assistant at the Federal Reserve Bank of Chicago prefers sleeping in a cold room. But his ground-floor apartment faces an alley: “There’s always people walking in and out, cars going up and down, and dogs barking.” So the windows stay closed.

Such is the case for many of us, as 53.2% of U.S. adults sleep with their bedroom windows closed, according to a November 2022 SleepFoundation.org survey. Some 60.9% of survey respondents keep their doors closed, too.

They may be missing out, according to Xiaojun Fan, Ph.D., a researcher at the Chair of Architecture and Building Systems, ETH Zurich, and the lead author of recent studies on the topic. Sleeping in a well-ventilated room may improve the air we breathe.

“[Poor] indoor air quality has been linked to many health effects,” Fan says, including increased stress on the body in the short term and respiratory diseases in the long term Trusted Source National Institute of Environmental Health Sciences As part of the National Institutes of Health, NIEHS works to expand scientific knowledge of human health and the environment. View Source . His studies built off of prior research that showed that keeping your window open, in particular, can reduce the bad things in our immediate atmosphere, help us sleep better, and even help us sleep longer Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. View Source .  

Other studies support this conclusion. A study published in Sleep Health Trusted Source Science Direct The leading platform of peer-reviewed literature that helps you move your research forward. View Source confirmed that CO2 levels, particulate matter and noise, as well as temperature, all influence sleep quality. A second study, published in Buildings Trusted Source MDPI Open Access View Source , looked at bedrooms where multiple people slept and found that as CO2 levels rise, sleep quality decreases.

Making sure our bedrooms have fresh air seems like an easy way to address sleep issues. So why aren’t more of us sleeping with a window open? And if we can’t keep a window or door open, what then?

Does Fresh Air Really Help Us Sleep?

We’ve heard for ages that breathing in fresh air is good for us. It helps clean our lungs, can increase our oxygen levels, and keeps our respiratory systems running smoothly. 

When it comes to affecting our bedroom environment, however, exactly how “fresh” that air is and what it can do for us are not as clear. Some studies have shown that air quality has helped people sleep in care facilities Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. View Source and think more clearly the next day Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. View Source .

Diving deeper into the topic may take you farther back in time. 

“Fresh air was thought to be the secret to good sleep in parenting books of yesteryear,” says Dr. Christopher Winter, a sleep specialist and neurologist in Charlottesville, Virginia, and host of the Sleep Unplugged podcast. He consulted Anna Steese Richardson’s 1914 book Better Babies and Their Care, for instance, which also extolled air’s benefits for curing nervousness and nail-biting.

Fan’s studies explored different details. Keeping a window open reduced concentration of carbon dioxide, volatile organic compounds, and some particulate matter in participant bedrooms, according to Fan’s 2022 study. People slept better. Keeping a door open also reduced carbon dioxide concentration, without a direct correlation to improving sleep.

Among SleepFoundation.org survey respondents who slept with the window open at least part of the time, 50.9% cited air circulation as the primary reason. A bit more, 55%, did so to regulate the room temperature, a number that dropped to 41.9% among respondents who kept a window open every night. In that group, the top response was getting better sleep (44.3%).

Dana Boldt, a 53-year-old lawyer in Los Angeles, is among that group. She and her husband sleep with a window open year-round and notice that they don’t sleep as well in a room without open windows.

“When the windows are closed, I just feel claustrophobic,” she says.

Weather or Not the Window Is Open

Of course, not all places are conducive to sleeping with the window open. In Boldt’s home state of California, with its mostly moderate climate, 52.9% of respondents sleep with their window open at least some of the time. 

Other folks who sleep with the window open: those who sleep in apartments (55.7%), those who sleep on the second floor or higher (54.6%) and those who live in the 10 coldest states in the country, based on average state-wide temperature (67.4%). That said, 43.5% of respondents in those states keep a window open only when the weather is warm.

Among respondents living in those chillier states, such as Alaska, Minnesota, and Wisconsin, 52.2% sleep with their bedroom or suite door open, too. Their primary reasons are pets (66.7%) and air circulation (41.7%).

As for the 10 warmest states, of which California is included: 64.9% of respondents sleep with windows closed. About the same amount in those states (64%) sleep with the door shut, too.

“Temperature [is only] a positive in some situations related to an open window,” Dr. Winter says. “If it’s hot outside, and the open window lets the cool out, not so much.”

Why We Keep Our Windows Closed

So why don’t more people sleep with the window open? People who sleep with windows closed, who comprised the majority of respondents, cited security concerns (36.2%), room temperature (33.5%), and noise (32.6%).

Indeed, research has found that noise can be such a disturbance to sleep that it outweighs even the benefits of an open window. A study that Fan co-authored Trusted Source Science Direct The leading platform of peer-reviewed literature that helps you move your research forward. View Source found that the bedroom air quality of 50 Shanghai residents improved when they slept with their windows open – but their sleep still suffered. The study was done in the summertime, so the bedrooms were hotter with the windows open, and noisier. In a hot, high-density city, “opening windows may disturb sleep and offset the positive effects of improving the ventilation,” wrote the researchers. “Thus, window opening should not be recommended as a universal way of achieving bedroom ventilation to promote sleep.” 

Instead, the study’s authors urged that solutions be found that ensure a bedroom environment with high air quality and good sleep quality without having to open windows or doors.

Where we sleep is a factor. The SleepFoundation.org survey found that 57.3% of respondents who live in single-family homes sleep with windows closed. For adults such as Epstein who sleep on the ground floor, 58.6% keep their windows closed, with the top reason being security concerns (41.4%). 

People who sleep with the door closed also are more likely to keep a window closed (53%) and vice versa (60.6%). 

Of those who sleep with the door closed, 55.3% do so for privacy, while more than a third say they do it out of habit (39.3%) and to get better sleep (39.2%). Another top reason was noise (34.6%) even though 77% described the area outside their home as quiet or extremely quiet. 

One good reason to keep that bedroom door closed is fire safety, though only 7.2% of respondents who sleep with the door closed give this as a reason. A closed bedroom door while you sleep can protect you from heat and smoke, while cutting off a fire’s oxygen supply and slowing its spread, reports the UL’s Firefighter Safety Research Institute.

When Open Windows Aren’t an Option

Among survey respondents, there was no noticeable difference in amount of sleep, sleep latency, or sleep disorders among people who slept with windows and doors open versus closed. 

But with Fan’s research in mind, we understand fresh air can be beneficial. So what do you do if you can’t open a window or door while you sleep? Fan suggests investing in an air purifier or filtration system, which 34% of respondents do.

In fact, a follow-up study by Fan found that participants slept more deeply and woke less frequently when their bedrooms were well-ventilated with a system of fans, as opposed to when they were not. The participants all lived in buildings in Belgium with centralized mechanical ventilation systems and wore trackers on their wrist as they slept. The researchers found that as they increased the ventilation, the participants’ sleep quality improved.

“Our study suggests that bedrooms should be ventilated with clean outdoor air,” Fan says, “or provided with air that is equivalent to outdoor clean air to improve its air quality.”

Methodology

The survey commissioned by SleepFoundation.org was conducted on the online survey platform Pollfish on Nov. 8, 2022. Results are from 1,250 survey participants in the United States who were 18 years old or older and regularly slept in a room or suite with a door and a window at the time of the survey. All respondents attested to answering the survey questions truthfully and accurately.