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Poor ventilation leads to a build-up of carbon dioxide in the bedroom To test the effect of keeping a window open, researchers tracked the sleep of healthy students. They slept with windows or doors either open or shut, and the room temperature was monitored. There was also a motion sensor in the pillow and one attached to the sleepers’ arm. Levels of CO2 were measured in the bedrooms over five days.
The result shows that lower carbon dioxide CO2 levels implied better sleep depth, sleep efficiency, and lesser number of awakening. With a window or door closed, the average CO2 level was 1150 parts per million, compared with 717 ppm when the window or door was open.
Humidity levels were similar in both conditions as were temperatures. This showed that an open window was better for reducing carbon dioxide CO2. The perceived freshness of bedroom air improved significantly when the CO2 level was lower.
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