dont EVER sleep under your covers. I started tracking my in-closet bed CO2 parts per million and the results are interesting. You can see CO2 jump from 500 to 600ppm when I go to bed at 1am. In the morning I did some reading under the covers for a while which I usually find calming— but maybe due to actual sedation. When I extended the covers to over the sensor, it detected 3.5k ppm, which is well over the safe limit (mental decline can be detected in cognitive tests at a threshold of 1900ppm)