Researchers study air quality in bedroom

The importance of ventilation for sleep quality and well-being is being studied in experiment involving subjects sleeping in climate chambers at DTU.

An experiment with ventilation in rooms where people sleep is designed to establish the importance of fresh air to sleep and well-being. Over a period of six weeks, ten subjects have spent four nights in a submarine-like climate chamber at DTU, where researchers can measure all the molecules in the air passing in and out of a perspex capsule.

“Little research has been conducted in this area, and the studies done so far have focused primarily on the ideal temperature in the bedroom, not on the air quality, which is what we’re looking at in this study,” explains Associate Professor Pawel Wargocki from DTU Civil Engineering, who is the lead supervisor of ‘The effects of ventilation in sleeping environment’, a project which is carried out by PhD student Xiaojun Fan.

Sleep quality

The aim of the project is to document the importance of ventilation and the supply of fresh air in relation to sleep quality and when the content of CO2 in the indoor climate begins to have a negative effect. The effects on sleep quality are recorded via a wristwatch, which can measure how quickly the subjects fall asleep, the number of times they wake up during the night, and whether sleep is light, deep, or REM sleep.

Experience from other international research in the field, which the researchers behind the current project have participated in, indicates that a concentration of 750 CO2 molecules in the air per million molecules, so-called ppm levels, does not negatively affect sleep, while levels above 2,600 ppm appear to.

“It’s not certain that we’ll be able to say, based on our study, that levels below 800 ppm have a positive effect. But we may be able to conclude at least that at levels of 1,000 ppm and higher, we can detect a negative impact on sleep quality,” says Pawel Wargocki.

Particles and organic compounds

The experiment measuring CO2 during sleep kicked off a year ago and will form part of a large study of sleep habits and air quality in Danish bedrooms. Other substudies are looking at factors such as air humidity, particle concentration, and levels of organic compounds. Following completion of all the substudies in 2022, the researchers will compile all their data and use them to plan a study with about 30 subjects, whose sleep quality will be measured in different scenarios with varying ventilation rates.

The ventilation and sleep study is being conducted in collaboration with Jiao Tong University in Shanghai, China, and has received USD 230,000 in funding from the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE).

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