There is a general pattern for which nostril a person breathes out of. Generally people switch the nostril they breathe out of every four hours. This can vary depending on your body position and nasal congestion, though. Richard Kayser, a nasal specialist, first recognized the “nasal cycle” in 1895. Your nose accomplishes the switch through erectile tissue in your nose.
The erectile tissue is, in fact, similar to the erectile tissue found in the penis and clitoris. The erectile tissue swells in the nostril almost completely blocking the passage while the erectile tissue in the other nostril shrinks down, allowing you to breathe through it.
The nostril that you are breathing out of can greatly affect your brain and body, too! A study done revealed that breathing through your right nostril can greatly increase your blood glucose levels while breathing through your left nostril has the opposite effect.
Another study found that breathing through your right nostril makes you consume more oxygen than if you breathe through your left nostril.