Most people spend ~90% of their time indoors — and indoor air is a powerful signal for the nervous system. High CO₂ and fine particles impair focus, decision-making, sleep, and long-term brain health. Simple, evidence-based fixes: • Get regular ventilation and fresh air • Service ventilation/HRV systems • Use purifiers and avoid indoor combustion • Monitor CO₂ and PM₂.₅ Small adjustments → measurable improvements in cognition, sleep, and overall wellbeing. #neuroscience #circadianrhythm #nervoussystemregulation #architecture #welbeing #healthylifestyle