My wife can’t sleep without a fan running. This has been a point of contention since early into ours relationship, as I still after 7+ years find I have much more restful sleep with it off.
BTW the biggest win in getting a good sleep for me has been making sure my bedroom is properly ventilated, so that I have low levels of CO2. Since I started doing that, my sleeping issues have been reduced to practically nothing - i.e. I almost never wake up feeling drowsy, which was something that happened to me a couple days a month before I started monitoring CO2.
It’s still all a preliminary field however.
Open a door and open a window. Pretty much nothing else does it, though an air exchanger in a home ventilation system can help.
This of course can get complicated by light (the door), sound (door and window), pollution (window) and heat/cold (window). So your local setup may vary.
In my own case the big challenge is winter. But usually just a small crack is enough to lower co2 a fair bit during the cold season.
Yep - I open a window in another room of my apartment, and the brownian motion air exchange (as both rooms have no doors) is enough to keep CO2 at around 600 ppm through the night. Without it, it'd probably shoot to over 2000 ppm over the night.
As someone with seasonal allergies, I've often been surprised at how serenely I'd sleep with a window open.