The nasal cycle explains why you're stuffed up on one side of your face

It's not an exercise bike for your nose. Instead, the nasal cycle is the biological cycle that automatically switches the bulk of your breathing from one nostril to another throughout the course of the day. It's the reason why you usually feel more stuffed up on one side when you have a cold but, as Matt Soniak explains at mental_floss, it's got some benefits, too.

One, it makes our sense of smell more complete. Different scent molecules degrade at different rates, and our scent receptors pick up on them accordingly. Some smells are easier to detect and process in a fast-moving airstream like the decongested nostril, while others are better detected in the slower airstream of the congested nostril. Nasal cycling also seems to keep the nose maintained for its function as an air filter and humidifier. The alternating congestion gives the mucous and cilia (the tiny hairs up in your nose) in each nostril a well-deserved break from the onslaught of air and prevents the insides of your nostrils from drying out, cracking and bleeding.