Airing out your room before bed: how the indoor climate influences our sleep
Fresh air in the bedroom can make an important contribution to a pleasant room climate. Even if we often do not notice it ourselves, high humidity and increased carbon dioxide levels can affect our sense of well-being. Ventilating the room before going to bed can therefore help create good conditions for a pleasant sleeping environment. But how often and for how long should you ventilate the room, and does it make sense to sleep with the window open all night? We have some answers and tips for you to help create a pleasant room climate in the bedroom all year round.
by CALIDA
September 10, 2025•4 min reading time
Ventilating before going to sleep: Fresh air helps create a pleasant room climate in the bedroom.
Table of Contents
The key points
Ventilating several times a day can help reduce carbon dioxide levels and humidity in the bedroom.
Ten minutes of intensive ventilation before and after going to bed can be a useful guideline; in summer, you can ventilate for longer if the outdoor temperature is sufficiently low.
Permanently leaving windows tilted open can be an option in summer. In winter, however, this can cool the room down more significantly and, under unfavourable conditions, encourage mould formation.
Ventilating before and after sleep: Why fresh air is important
Over the course of the day, carbon dioxide (CO₂) can accumulate in a room – especially when several people are in the room with the windows closed. You may be familiar with this type of air quality from offices. With the windows closed, the air can change relatively quickly. Increased CO₂ levels can be associated with tiredness or difficulty concentrating.
Air quality in the bedroom can also affect your personal sense of well-being. Ventilating before going to bed reduces humidity and provides air exchange: stale air is released outside while fresh air enters the room. At the same time, regular ventilation can help keep humidity within a suitable range and reduce conditions that can contribute to mould formation.
Leaving the window open all night? Advantages and disadvantages
As long as noise, draughts or allergies do not disturb your sleep, leaving the window open at night can feel pleasant during warm summer nights. With the window open, carbon dioxide levels can remain lower, as air is continuously exchanged.
Cooler air can also contribute to a pleasant room climate while you sleep. This can be particularly useful when the bedroom has heated up during the day.
In winter or at cooler temperatures, however, some caution is advisable, as permanently open windows can cool the room down considerably. This may cause the heating system to adjust more frequently and can make the air drier. Regular, short periods of ventilation can be a suitable alternative in these conditions.
Lower carbon dioxide levels in the bedroom
Studies investigate the relationship between carbon dioxide levels in the bedroom and sleep quality. As a general guideline, values below 800 ppm (parts per million) are considered an indication of good indoor air quality. At values above 1,000 ppm, the air may be perceived as less pleasant.
Just a few hours after closing the windows, carbon dioxide levels in a bedroom can rise noticeably. This is one reason to ventilate the bedroom not only before going to bed, but also regularly during the day and after getting up.
Cooled-down rooms and humidity
A room temperature of around 16 to 18°C can feel pleasant in the bedroom. However, significantly lower temperatures can mean that the air is able to hold less moisture.
During sleep, breathing and perspiration also introduce additional moisture and heat into the room air. When humid air comes into contact with particularly cold surfaces, condensation can form. If humidity remains high for an extended period, this can encourage mould formation. For this reason, you should avoid keeping windows open continuously in autumn and winter and instead ventilate regularly for short periods. This allows humidity and CO₂ to leave the bedroom without cooling the room down too much.
How to ventilate properly in every season
You now know why ventilating before going to bed can be useful and what to keep in mind. Here is an overview of the most important tips.
How to ventilate in spring & summer:
Ventilate for at least 20 minutes before going to bed, ideally with the window fully open.
During periods of extreme heat, wait until the outdoor temperature has dropped in the evening before ventilating. When temperatures are comfortable, you can also leave the window open throughout the night.
Extra tip: To create a pleasant sleeping environment on warm summer nights, you can also opt for breathable CALIDA nightwear made from suitable materials such as TENCEL™.
And how to ventilate in autumn & winter:
Ventilate intensively for five to ten minutes several times a day to let fresh air in without cooling the room down too much.
Turn off the radiators briefly before ventilating and switch them back on afterwards. This can help reduce unnecessary heat loss.
Extra tip: With warm and cosy pyjamas, you can enjoy comfortable sleep even at cooler room temperatures. Materials such as wool-silk can support a balanced feel while wearing them.
Conclusion
Ventilating before going to sleep is a simple way to influence the room climate in your bedroom. Regular ventilation can help reduce humidity and CO₂ levels in the room and provide pleasant air exchange.
Always adapt your ventilation routine to the season and the conditions in your room. A room temperature between 16 and 18°C can feel pleasant in the bedroom. Combined with comfortable, temperature-balancing sleepwear, you can create a personal sleeping environment that suits your individual needs.
Discover more interesting blog posts:
