You tried sleeping with a window open?
My bathroom is a Jack-and-Jill (-ish) design. Beside my bed is a door to the bathroom which is left open at night and another left open to the hall landing. The bathroom and landing windows are normally left open too. (Naturally, doors get closed when there are guests in the house, and windows get closed in cold weather to retain heat.)
Stuffiness in the bedroom isn't the problem. I just have a dread of struggling with sleep after past years with insomnia. Now that I don't have to get up to go to work I just wait until I am so exhausted that I can no longer stay awake. The trouble is that even though I don't typically don't get up until (say) 10:00-11:00, I would still only have had 5 to 6 hours sleep and often not really restful sleep at that. It is now 1:25 pm and I still feel half asleep!
If I am doing something that requires me to get up early I just get by on a few hours sleep. My regular blood tests are often before 09:00 so I get up at 08:15 for them and try to have a nap after I get back.
I have sometimes gone to sleep at 04:00, got back up at 06:30, left the house at 07:30, travelled an hour and a half to start a forum ride somewhere else, cycled for 11+ hours, travelled an hour and a half home, got back about 22:00, showered and eaten food until 23:00 and STILL not gone back to bed before midnight! It takes total exhaustion or serious illness for me to got bed
before midnight. I'm sure that it isn't a healthy thing to do!
I'll try going to bed and getting up a few minutes earlier each day until I am sleeping (say) 01:00 - 07:00. That would be a big improvement in that I would have all the hours of daylight available to me in winter, rather than just the 4 or 5 hours that I often see.