What is Lüften, the Cold Weather Sleep Trend Going Viral on TikTok?

SleepTok is at it again. There’s a new trend to add onto your feet-cricketingbed rotting, and sleepy girl mocktail-ing. This trend, a common practice in Germany called “Lüften”, has some people breathing in the crisp winter air and others cringing at the thought of precious heat escaping their windows.

Why Are People Opening Their Windows In the Winter Before Bed? 

TikTokers are opening their windows in freezing temperatures in hopes to improve their sleep and indoor air quality. One video with over 200,000 likes shows a parent, Kaitlin Klimmer, opening her child’s bedroom windows before bed as they’re going through their bedtime routine. Klimmer says she puts hot water and heating pads in her kids beds and then “[closes] the door to trap all that cold air in the room.” (1)  

“While the room is “Lüften,” everyone is going through their bedtime routine and by the time they’re done, the room is cold but their bed is warm,” says Klimmer. The video then shows Klimmer closing the bedroom window as her child drifts off to sleep. “Fresh cold air makes us feel sleepy,” the TikTok creator explains.

Other content creators on the platform explain that Lüften isn’t just meant to cool down a room; opening the windows for a few minutes, even in the winter, can prevent mold and moisture accumulation. 

It’s important to note that “Lüften” isn’t meant to be practiced all night, but in short periods throughout the day. As quoted in Politico, researcher Raymond Galvin explains, “The correct way to ventilate a home is to employ the Stoßlüften, or shock ventilation method. You open your windows completely for three minutes if it’s windy, five to 10 minutes if it’s not.” (2)

Opening your home to fresh air does make sense in theory, but does it work and is it worth a try? And, should we open our windows all night while we’re sleeping, or is it better to practice Lüften for just a few minutes each day in the winter? 

Why “Lüften” In the Winter? 

Some studies have found an association between increased room ventilation and improved sleep quality. For example, a 2022 Danish study found that opening a bedroom door or window improved sleep quality and indoor air quality. (3) However, this study involved opening the windows throughout the night, which might not be possible for everyone. 

Dr. Shelby Harris, Director of Sleep Health at Sleepopolis, explains, “Outside temperatures, especially in extreme climates, can impact the temperature of your bedroom, potentially disrupting your sleep.” (4) While sleeping in a cool room can be beneficial for sleep there’s certainly a limit on how cool you can go, and leaving the windows open all night in the winter may be too extreme for some. 

Noise can also be a huge sleep disruptor, as Dr. Harris explains; “Sleeping with your window open if you live in a noisy area, near a busy street, or have neighbors who make noise during the night, could lead to increased sleep disturbances and a lower quality of sleep.” (4) 

While opening your windows in the dead of winter may have some benefits for ventilation, a skyrocketing utility bill might keep you lying awake at night questioning whether or not Lüften is worth it. 

For those that want to keep their homes sealed away from the outside elements, an air purifier might be of interest. And, it’s a good idea to visit a doctor if you’re experiencing sensitivities to air quality in your house or apartment. 

Considering the drawbacks of leaving the windows open all night, Lüften seems like an easier, and more comfortable, approach, with just a few minutes of open windows and cold air each day. Just make sure to check the weather!