Why you should sleep with the windows open — even in winter

The image shows a woman sleeping in bed with her window open in Lüften’, a German sleep hack
(Image credit: Getty Images)

As sleep experts, we take most of the sleep hacks that come out of TikTok with a healthy air of scepticism. But occasionally the social media platform can produce unexpected gems, like the ‘lüften’’ sleep method currently doing the rounds, which promises to improve sleep quality by opening your bedroom windows before bed — even during winter.  

In a video posted by baby sleep coach Kaitlin Klimmer that has been viewed over 220,000 times, the young mum cites the benefits of ‘luften’, which is the German word for ‘air out’. Klimmer, who lives in Austria, uses ‘lüften’ to drastically reduce the temperature of her family’s bedrooms in order to improve their sleep quality. 

Here, we’ll explore what ‘lüften’ is, why it works, and how you can use this German sleep hack as part of your own bedtime routine. Of course, 'lüften’ will only improve your sleep quality if your sleep hygiene is otherwise up to scratch. That means removing clutter from around your bed, having a regular bed and wake time, as well as ensuring that you’re sleeping on the best mattress for your sleep style. 

What is lüften and how can it improve your sleep?

Roughly translated from German, 'lüften’' means to 'air out.' This practice, which is deeply rooted in German culture, involves ventilating the home, even during winter. Klimmer uses lüften to reduce the temperature of her and her family’s bedrooms in the run up to bedtime in order to reduce the time it takes for them to fall asleep, as well as helping them stay asleep for longer.


♬ original sound - Kaitlin [Baby Sleep]

“We’ve all seen the videos of the Danish babies sleeping outside in the winter,” says Klimmer. “But since I’ve moved to Austria, I realized that they use the same principles of cold and fresh air to help everyone get better sleep but in a bit of a different way. They do something called ‘lüften' which is when you open all the windows in a bedroom to make the room as cold as possible.”

In the video, Klimmer then displays how she opens the windows wide, allowing the cool night air to permeate the room. With temperatures dropping as low as 23° F (-5° C) during Austrian winters, the bedroom becomes drastically cooler. 

Why is sleep temperature so important?

The relationship between room temperature and sleep quality has been well documented, with studies suggesting that the best temperature for quality sleep is between 20 and 25 °C (68 and 77 F). Our core temperature drops when we get tired, which helps our body prepare for sleep. This is why we get tired when we get sleepy. 

This necessary temperature drop can become disrupted during the hotter summer months, when it's harder to cool down. However, bundling up under layers and turning the thermostat up during the cooler winter months can have a similar negative effect on our sleep.  

Instead, embracing a cooler sleep environment can help facilitate this natural drop in body temperature, signaling to your body that it's time to sleep. 'Lüften' helps prepare our bodies for sleep. 


Step 1. Open you bedroom window 

A woman sleeps peacefully in her bed under a white duvet, while a small stack of books can be seen on her bedside table

(Image credit: Getty Images)

Open your bedroom window wide, allowing the cool air to permeate your bedroom. You'll need to open your curtains and blinds to ensure that the cool air circulates throughout the room.

Step 2. Close your bedroom door

Once your window and curtains are open wide and then close your bedroom window to trap all that cool air inside your bedroom (and keep the rest of your house nice and warm). “We put hot water bottles and heating pads in our kiddos beds just so it’s nice and cozy and then we close the door to trap all that cold air in the room,” says Klimmer.

Step 3: Use a hot water bottle 

Although your bedroom is cool, place a hot water bottle in your bed to ensure your bed in warm. Keep your window open while you begin your nighttime routine.  “While the room is ‘luften’ everyone is going about their bedtime routine and by the time they’re done the room is cold but their bed is warm.”  

Nicola Appleton
Sleep Features Editor

Nicola Appleton is Sleep Features Editor at Tom’s Guide, specialising in quality news content surrounding sleep and wellbeing. Nicola cut her teeth as a journalist in a busy newsroom in Bristol, UK, 15 years ago as part of a team at Britain's largest independent press agency. Since then, her job as a journalist has taken her to the States, to Sydney, and then back to Blighty, where she has written and edited features for a whole host of prominent British and international brands, including  The Independent, The Sydney Morning Herald, HuffPost, Refinery29, Stylist and more. As well as tackling the vast topic of sleep, Nicola will be joining the raft of expert mattress reviewers at Tom's Guide, helping steer readers towards the very best mattresses on the market.