Should bedroom windows be closed at night? This is a question sleep experts and security experts get asked a lot, read on to find out what they say…

The key things to consider with regards to deciding whether to have bedroom windows open or closed at night are:-

  1. Sleep quality
  2. Hygiene
  3. Security

Of course, for security a locked window makes the most sense, especially given that 20% of burglaries in England and Wales are through windows. However, Jackloc window restrictors enable windows to be opened to a maximum of 100mm while being secured even against attempts to force the window wider.  This restricted opening window option means that you can rest assured that your home is secure while having a window partially open.  But why might we want partially open bedroom windows at night?

Sleep Quality
It is now widely known that sleep quality has a huge impact on our mental and physical health. One of the main reasons for sleeping with a bedroom window open is that doing so can improve our quality of sleep, ensuring we wake up feeling fully rested.

Scientists have found that a room temperature between 16° and 18°C is ideal for sleeping at night, although this varies by individual. Within this temperature range the body’s natural temperature regulation is aided and melatonin production is boosted. Melatonin is a crucial hormone that regulates sleep and it is produced more effectively in cooler conditions.  With night time temperatures in many houses and apartments higher than this in the summer, especially in attic bedrooms, the easiest way to achieve cooler temperatures is to slightly open a window.

Temperature isn’t the only factor in sleep quality though. A study published in Sleep Healtht CO2 levels and particulate matter both influence sleep quality. This was supported by a study published in Buildings thatlooked at bedrooms where more than one person slept and found that as CO2 levels rise, sleep quality decreases. Fresh air from a partially open window helps lower carbon dioxide levels in your bedroom.

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 effect of air quality on sleep says that poor room air quality is linked to many negative health effects, including increased stress on the body in the short term and respiratory diseases in the long term.

Josh Mitchell, HVAC expert and owner of Air Conditioner Lab, says that during the winter he often finds that homes are not ventilated properly which leads to a build-up of pollutants in the home. Josh said ‘It is essential that you displace some of these pollutants such as CO2, and normally the quickest and easiest way to do this is through opening a window’.

Coughs and colds also have a negative impact on sleep quality and can be affected by whether a window is open or not. As we learnt during the Covid pandemic, sleeping with a window open can help reduce the risk of transmitting germs amongst household members. If you already have a cold, having a bedroom window open can also prevent stuffiness when sleeping with a blocked nose.

Disadvantages of open windows at night
But what about the disadvantages of opening bedroom windows at night? Hay fever sufferers might want to close windows at night during spring and summer due to the pollen shower phenomenon – this is when during the day hot air rises and, with this, pollen is carried alongside it. At night, the air cools down, beginning a downward drift, and the pollen then falls with the air, so this is why you are more likely to wake up with hay fever symptoms during the night.

There is also the consideration of traffic fumes and, of course, noise which can be a nuisance in urban and rural areas whether caused by humans or animals!

If these considerations are of concern to you it might be better to make sure that you regularly ventilate your bedrooms during the day, regardless of whether you keep your window closed or open at night. It is widely recommended that we should all ventilate all rooms three to five times a day for ten minutes at a time. In cold outside temperatures, five minutes are sufficient. It is especially recommended that windows be opened to air the room shortly before going to bed, as long as you don’t suffer from hay fever.

Many people don’t ventilate their homes this often due to concerns about security, but Jackloc’s incredibly strong and secure window restrictors enable you to open windows to 100mm but are secure against being opened any wider. This means you can benefit from a well-ventilated home without the risk of anyone falling out of an open window or of anyone entering your home.

We hope that this article helps you to consider the question ‘should bedroom windows be closed at night?’