I use an Airthings device to measure the air quality in my bedroom. I'm noticeably more groggy in the morning if there is more than recommended CO2 in the room.

I use an Airthings device to measure the air quality in my bedroom. I'm noticeably more groggy in the morning if there is more than recommended CO2 in the room. I don't care that much about the other things it measures. Another nice feature is having all of the history on my phone.