Why do you sometimes feel like chewing on something?

In fact, despite the seeming simplicity of the question, it is enough to answer it in a nutshell. In general, the general model of habit formation and maintenance suggests that this behavior is associated either with something pleasant or with the cessation of exposure to something unpleasant (see matching law).

Research shows that autostimulation ( self-production of stimuli, which includes biting pens, stimulating the oral cavity; and biting nails, stimulating the mouth and fingers) most likely does not carry positive stimulation and helps us to control stress levels (reduce negative stimulation).

One of the possible mechanisms of this effect is a decrease in the activity of the network of the passive mode of the brain. This neural network is activated during "downtime" in work, which, paradoxically, can occur even during active work. During her work, we come up with new ideas, but, in addition, we are engaged in self-digging and reflection on abstract topics.

This causes a certain stress (associated mainly with metacognitive processes, responding to the fact of distraction). Accordingly, the presence of an additional source of stimulation can increase the complexity of the work and thus help avoid problems with concentration, and according to the matching law, we tend to reproduce the behavior that helped to avoid trouble.

This is an instinctive desire caused by a lack of minerals in the body. At least - calcium, but maybe not only calcium. Calcium gluconate is sold in any pharmacy, it is cheap, and the myths that it is poorly absorbed are created by those who sell expensive supplements and vitamins.