If your bedroom is poorly ventilated, CO2 is likely to accumulate, making you less comfortable and potentially damaging your health. Research shows that concentrations of carbon dioxide when people are sleeping are between 3 to 5 times higher in bedrooms where the window is shut.⁠ ⁠ People tend to feel that the air is fresher when they open a bedroom window or use a fan, and there’s evidence that suggests they’re likely to fall asleep more easily in a properly ventilated room. In the scientists’ experiments, they found that ventilation helped subjects to feel better rested and more alert after their night’s sleep.⁠ ⁠ _____⁠ ⁠ Carbon dioxide is also linked to conditions like sleep apnea, and some experts now believe that CO2 triggers neurons (brain cells) that can rouse you from your sleep. If you have difficulty sleeping, it’s unpleasant and upsetting to be jolted awake just as you begin to drift off.⁠ ⁠ If you think CO2 is affecting your night’s rest, then it’s important to get air ci...