The frosty winter months often conjure images of crackling fires, oversized blankets, and winding down in warm, cozy rooms. However, a German trend could inspire you to open the windows and let in some cold winter air for better sleep.
This practice is called lüften, which quite literally translates from German as to ventilate or air out. “Lüften is a German…[practice of] ventilation or getting the air out of a room to make the air fresh,” says Dr. Valerie Cacho, an integrative sleep physician. The practice is most applicable in the cold winter months when air can feel stuffy indoors.
Lüften has recently been gaining attention on social media, with many users sharing their experiences learning about the German practice. While lüften doesn’t require you to leave your windows open around the clock, many devotees claim that sleeping with your windows open is the key to getting better sleep.
But does lüften work for better sleep? And if you decide to give lüften a try, how can you safely leverage the practice to drop the temperature in your room — and improve your sleep in the process?
What are the benefits of lüften?
Lüften involves opening windows in order to air out a space and improve air circulation, replacing stale indoor air with fresh outdoor air. This can improve air quality in the room and keep the air from getting too dry. “Opening a window reduces CO2 that has built up from our breathing and from CO2 emitted from gas heaters,” says Cacho, who also shares that this improvement in air quality can support better rest.
In a recent study by Chenxi Liao published in Science and Technology for the Built Environment that looked into the sleep quality effects of having open or closed windows in the bedroom environment, researchers found some benefits to open windows. The study found that participants snored and woke up significantly less often when sleeping with windows open. They also found that “people who sleep with their windows open report feeling that the air is fresher [than] that of recycled air from a poorly ventilated room,” says Cahco.
But opening the windows doesn’t just get fresh air into the home; in the winter, leaving the windows open will also drop a room’s temperature — and colder temperatures are associated with better sleep.
“When you sleep, your core body temperature drops,” says Cacho. “If the room is too warm, it can counteract your body’s ability to fall asleep.” On the flip side, a cooler room will naturally match your body’s drop in temperature, making it easier to fall and stay asleep. While people will differ in their “perfect” sleep temperature, for most, the ideal temperature will fall somewhere between 65 and 67 degrees Fahrenheit.
The positive effect of cool temperatures may also be a reason some cultures promote having their babies sleep outside. For example, in Finland, allowing babies to nap outdoors is common, with some parents reporting their babies sleeping longer outdoors versus indoors.
What are the drawbacks of lüften?
Because it improves air quality and lowers the temperature in the home, lüften may have the potential to help people get better sleep. But the practice isn’t without its drawbacks.
In the Liao study cited earlier, participants who slept with the windows open did not report better sleep with the improved air quality. Rather, they reported higher noise levels, worse well-being, and feeling less rested than those who slept with windows closed. Sleeping with the windows open may also cause anxiety (for example, people might worry about potential intruders), which can make it hard to fall asleep.
And while cooler temperatures are ideal for sleep, practicing lüften in the winter can create too much of a good thing situation. “If it’s too cold outside and your body temperature drops to the point when you are shivering, it can be hard to fall asleep or stay asleep,” says Cacho.
Dropping temperatures too much can also put you at increased risk for illness.
How to get the most out of lüften
Like any practice, lüften has its pros and cons — and while it may work great for some people, it may not be the right fit for others. That said, if you want to give lüften a try, here are a few tips you’ll want to keep in mind to help you get quality sleep.
Don’t leave the windows open all night
You don’t need to leave your windows open all night in order to experience the benefits of lüften. In fact, sleeping with your windows on for the entirety of the night can increase your chances of experiencing sleep disturbances (like loud traffic noises) or negative effects (like getting sick). Instead, “find the balance between getting enough fresh air and ventilation to drive out CO2 levels with a comfortable temperature that supports your sleep,” says Cacho — for example, by opening the windows for a few hours before bed and then shutting them right before you go to sleep.
Make sure windows are secure
Opening the windows can let fresh air into your room — but that’s the only thing you want to let in. If you are leaving your windows open for prolonged periods — particularly if your room is on the ground floor — make sure to have secure screens or other protective mechanisms to keep out intruders and pests.
Monitor temperature and air quality
If you live in an extreme climate where temperatures regularly dip below freezing, it’s important to keep an eye on the temperature, as sub-zero temps will likely mean it’s safer to sleep with your windows closed. “Temperatures that are freezing and below can be detrimental to health,” says Cacho. In those instances, set your thermostat to a cool temperature that promotes better rest.
Likewise, one of the benefits of lüften is getting fresh air into a room — but if the air outside isn’t safe to breathe, it’s best to leave the windows shut. Before sleeping with your windows open, make sure to monitor the air quality.
