Do you have a need to chew? Fingernails? Ends of pencils? Gum? There may be a reason for that.
The trigeminal nerve innervates the jaw joint. When it is stimulated, it releases serotonin. So moving the jaw, whether it's while eating, grinding your teeth in your sleep, clenching your jaw during the day, eating CRUNCHY foods like popcorn, or chewing ice cubes or gum, may have mild antidepressant effects.
On another website, I mentioned chewing ice cubes and it quickly became one of the most popular search terms bringing web surfers in. It's clear, a lot of people do this to the point where they wonder why.
In balance, there is probably a good purpose for this. However, in excess, as in temporal mandibular joint (TMJ) syndrome, it can cause other problems.
You may want to do an experiment with yourself and see how you feel after a day of eliminating non-nourishing chewing. Do you feel irritable? Anxious? Out of sorts? Maybe you're dependent on your jaw in a way that may be best served by other outlets.
Remember…talking about how you feel, yawning, even singing…also move the same joint.