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How was your sleep? Here's to better rest and recuperation

Ever thought about when sleep is discussed in our everyday lives? A non-academic field research tells me that it is primarily when we are not sleeping well, when we are disappointed with how it feels when we wake up in the morning and when we try to put the finger on what disturbs our much deserved sleep. I’m Åsa Norén-Lundh, one of Swegon’s experts – not specifically on sleep quality, but I know I have an answer to why some are not sleeping well. Learn more about sleep and indoor climate in this blog post.

While we take great care about what we eat and drink to keep ourselves productive and healthy, we rarely think about the air we breathe. We need 0,75 kg of food and 1,5 kg of fluids every day, and a remarkable amount of nearly 10 000 litres of air, inhaled and exhaled daily(!). If we knew the latter, air quality and indoor climate would probably have gotten the attention it deserves.

In modern society, we spend many of the day’s 24h inside controlled environments, indoor spaces separated from the outdoors’ natural variations. This is sometimes good, considering the possible weather alterations, but it requires that the indoor spaces offer a good indoor environmental quality in order to nurture our needs as living human beings. Good indoor environmental quality could be described as a climate inside our buildings which promotes good health and well-being.

Now, when we are indoors, we devote quite some time to rest and recuperation. In fact, during an average lifetime as much as one third, or 28,3 years, is spent on sleep. Most often these hours are spent indoors, at home or occasionally in a hotel, it is more rare that the regular sleep happens outdoors. WHO states that, in 2024 air pollution is the most important factor in regards to environmental health risks in Europe. It causes various health issues, but has a particular link to respiratory and cardiovascular diseases.

So, with all this knowledge, ever thought about the air quality, or the entire indoor climate, where you sleep?

What affects the indoor environmental quality?

Today, health risks of more obvious kinds have been eliminated from our indoor environments, for instance are households and industries no longer dependent on fuming fireplaces, and indoor smoking is widely avoided or banned. However, research shows that there are still factors in different indoor environments which adversely affect good health and well-being. Poor air quality, emissions from materials, draughts and noise, too high or too low humidity levels, as well as higher temperatures all have a negative impact on health and well-being.

So, it is stated above that a variety of parameters have a negative effect on the human being, and that goes for both waken hours as well as for the time of sleep. What I am trying to say, is that the poor sleep quality is in many cases purely related to poor indoor environmental quality.

So, at what point does this happen?

There are numerous studies which indicate that the quality of sleep varies with the air quality in bedrooms. It is established that levels of carbon dioxide (CO2), between 400-800 parts per million (ppm) are more or less optimal in order to wake up thoroughly rested and feel focused. To achieve those levels, bedrooms need to be ventilated. Not only will ventilation extract the air we have exhaled in the indoor environment, but it will also to ensure a good supply of fresh air, day as night.

Urbanisation causes living spaces to be used in various ways throughout the day. It is common that bedrooms have to be office stations during the day, that the children’s rooms are used for gaming, playing and hang-out with friends until late evenings which means that the rooms used for rest and recuperation are filled with electronics, plastics, textiles and human bodies which all emit different pollutants to the indoor air. Worst case, doors are closed or nearly shut during the night to not disturb each other, which reduces the air movement. There is an obvious risk that no one wakes up clear and rested in the morning.

Ventilation is key – but not by opening a window

With the above said, it might seem easy to just open a window and let the pollutants out, and “fresh” air in. But that is starting to become a big no-no since when a window is opened, draught and noise is with today’s urbanisation and “around the clock” city activity more or less inescapable. In addition, the air is far from fresh in many places around the globe. It is rather highly polluted in urban areas and it enters the bedroom completely unfiltered adding to the pollutants already emitted inside. Mechanical ventilation is key for air quality as it significantly reduces the risk of draught, and the soundscape from modern ventilation is not to compare with the clatter and clank that an open window lets in.

Humidity is most often reflected upon as a bad thing, and most often in relation to too high levels. In regards to sleep, a too high level of humidity can make the bed feel damp which in turn can intrude on a good night’s sleep. It is though vital to point out that even too low levels of humidity can disrupt a person’s sleep. Issues with chapped lips, soar noses and itchy skin can keep a person awake at night, and low levels of humidity often cause morning headaches and irritation to the eyes. Further, a humidity level of 40-60% is so far known as favourable to hinder transfers of airborne diseases. However, more research is needed to define what humidity levels are the best, depending on situation and environment.

Further, sleep researchers have for years known a lot about temperature and have recommended 19°C and 21°C in bedrooms. This because their extensive research have found that normal to lower temperatures are beneficial for good sleep quality however, they also recognise that some prefer 16 to 18°C and enjoy a thicker blanket or flannel pyjamas, and they seem to wake up bright and well-rested in the morning. The same does not apply to the ones who have spent the night in a bedroom a few degrees above 21°C.

Learn more

Ventilation is the way to tackle poor air quality and it is actually proven in research that it is not only improving the feeling of being better ready for the next day, numbers are showing that a person’s overall performance can increase by as much as 20% after a good night’s sleep. Ventilation is though important to think through. We should at this point, have come far beyond opening a window, since we know that the outdoors can cause issues with noise, draught and air pollution. Well thought through, correctly installed and commissioned mechanical ventilation is absolutely the way forward. We share our profound knowledge and expertise in both our Knowledge Hub at Swegon.com and at Swegon Air Academy, where we are honoured to present the forefront of current research and academia related to indoor environmental quality. Last but not least, we are also here to help you in person!