Yes. I feel much more alert, but oddly I have a much harder time falling asleep. I've since started regular low-dose melatonin which helps a lot. In particular

Yes. I feel much more alert, but oddly I have a much harder time falling asleep. I've since started regular low-dose melatonin which helps a lot. In particular I find I am much less groggy in the mornings, and stepping outside doesn't feel like a breath of fresh air. The changes I made are not options for most. I have an industrial rooftop HVAC unit for a space about 5x larger than my home. The fans run continually and there is no fresh air exchange per se but part of the return duct runs through the attic which is not air-tight, more of an open cavity. I change the air filter every 3 months and keep the returns clean by vacuuming regularly. I try not to close doors to encourage circulation, and my bedroom door had an vent to the hall above it -- not sound or light proof, but doesn't restrict airflow. The key that I've found is airflow. A closed room and a bunch of fans won't help you, but circulating the air of your entire home will make a big difference. It's important that your home breathes. An airtight home is actually very unhealthy, though heating/cooling is more efficient. Lastly, cooking is the worst offender for poor air quality. Having a stove-top exhaust hood that actually filters and vents outside is so important. Cooking without exhaust or fresh air can easily bring the kitchen and surrounding areas near 1000ppm in under an hour. I keep my exhaust vent on more often than not and it makes a big difference. Negative air pressure is good: air is pulled in from outside.