Why one nostril always feels blocked - and what it may do to your brain

If you've ever felt that only one nostril is truly "open," you're not imagining it. It's a well-known natural phenomenon called the nasal cycle, in which airflow is greater through one nostril before gradually shifting to the other. The nasal cycle has been documented in previous research. More recently, scientists have also examined what happens when people intentionally breathe through only one nostril and whether that affects brain activity, mood and mind wandering. Throughout the day, the nostrils alternate in dominance, with one carrying more airflow than the other. This shift can occur about every two hours while a person is awake and less frequently during sleep. The process involves alternating congestion and decongestion of the nasal tissues and is thought to allow the nasal lining to rest, stay moist and help protect against pathogens, according to CNN.