The idea
A small closed bedroom fills with exhaled carbon dioxide overnight. In one study, people slept measurably worse at 1,000 parts per million than at 750, and closed student rooms have been measured at more than double that. Heat and noise do damage too.
Air monitors and sleep trackers both exist, but they do not talk to each other. The one product that joins them costs US$549 and only works with its maker’s ring.
Build plan
- A CO2, temperature and humidity sensor
- A microphone that records loudness only, never audio
- A light sensor and an ESP32
- An app that pulls sleep and heart rate from your wearable and compares nights
Honest limits
The answer may turn out to be “open the door”, in which case a A$50 monitor would have told me the same thing. I plan to run that cheap test before building anything.