I worked in an office where fatigue and even headaches became regular by 2 PM. We decided to test the theory using real-time indoor air quality monitors, and the data shocked us. CO₂ levels were peaking right after lunch, reducing alertness. Once we saw the numbers, it was easier to get management to improve ventilation and add some purifiers. Within a week, the difference was obvious — people were more awake, meetings went smoother, and the general vibe improved. It's a smart move if you're noticing energy dips at the same time daily.