In the most recent episode of SciShow, host Hank Green explains the nasal cycle, a process in which nostrils trade off congestion with each other in order for the body to be able to detect a greater range of smells.
Every couple of hours your nostrils switch places between being mostly stuffed and all stuffed. Why is your body doing this to you? Well actually your nostrils do this to you all the time, you just notice it more when you’re congested. It’s called the nasal cycle and about 8 out of every 10 people experience it to some degree. To people who have a nasal cycle, one nostril is more swollen than the other, restricting the flow of air every four hours or so. The swelling in the first nostril goes down and goes up in the other. Now there are reasons for this and it has to do with why you have two nostrils in the first place. Besides that it’s super cute. Having two nostrils lets them split the workload it makes you a much better smeller.