Is it true that we only breathe through one nostril at a time?

Breathing is almost a subconscious activity. Most of us think that we breathe through both nostrils at the same time. But did you know that we breathe through only one nostril at a time? In fact, about 85% people of the world do that. The thing is that it is barely noticeable and none of us get aware of it until we have some breathing problems.
The phenomenon is the part of our natural nasal cycle. We switch between breathing through each nostril in a cyclical fashion. It takes between two and three hours for the switch to take place. It can depend on the individual and the position he is reclining in.
The first person to describe the nasal cycle was the German physician Richard Kayser in 1895. He found out that the reason for this phenomenon is the tissue called erectile tissue in nose, similar to the tissue in penis or clitoris. The erectile tissue swells up in one nostril at a particular point of time whereas shrinks in the other. The swelled tissue blocks the corresponding nostril while creating a path in the other one. The nostril is not completely blocked, however. After a couple of hours, the shrunken tissue swells and the other one shrinks. The activity of erectile tissue is controlled via our nervous system by hypothalamus.
We can also control through which nostril we breathe. If we close one nostril, the erectile tissue will shrink in the other, opening a pathway for air. This also happens when we lie on one side. When we are lying on a side, the tissue in that side will swell up after a few minutes. For example, if we are lying on left side, the erectile tissue in left nostril would swell up and shrink in the other. Scientists have concluded that this is the reason why we often change sides while we are sleeping even if we feel no discomfort in that position.
Interestingly, studies have also revealed that continuous breathing through one nostril can alter metabolic functions in our body. Breathing through right nostril exclusively increases oxygen consumption in a greater rate than the other. It has been also found that breathing through a nostril increases the activity of the brain hemisphere on the other side. That is, breathing through right nostril increases the function of left hemisphere and the right one is more active when you breathe through the left nostril.
This alternate breathing benefits humans in a number of ways, like providing the ability to detect a great range of smells.

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